Signaling for inter prediction in high level syntax

ABSTRACT

Systems, methods and apparatus for video processing are described. The video processing may include video encoding, video decoding, or video transcoding. One example method of video processing includes performing a conversion between a video including one or more video regions and a bitstream of the video according to a format rule. The format rule specifies that a variable X indicates whether B slice is allowed or used in a video region. The format rule further specifies that the variable X is based on values of a reference picture list information present flag and/or a field indicating a number of entries in a reference picture list syntax structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2021/085772, filed on Apr. 7, 2021, which claims the priorityto and benefit of International Patent Application No.PCT/CN2020/083569, filed on Apr. 7, 2020. All the aforementioned patentapplications are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to image and video coding and decoding.

BACKGROUND

Digital video accounts for the largest bandwidth use on the internet andother digital communication networks. As the number of connected userdevices capable of receiving and displaying video increases, it isexpected that the bandwidth demand for digital video usage will continueto grow.

SUMMARY

The present document discloses techniques that can be used by videoencoders and decoders for processing coded representation of video usingcontrol information useful for decoding of the coded representation.

In one example aspect, a video processing method is disclosed. Themethod includes performing a conversion between a video having one ormore chroma components, the video comprising one or more video picturescomprising one or more slices and a coded representation of the video,wherein the coded representation conforms to a format rule, wherein theformat rule specifies that a chroma array type field controls aconstraint on a conversion characteristic of chroma used during theconversion.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video comprisingone or more video pictures comprising one or more video regions and acoded representation of the video, wherein the coded representationconforms to a format rule that specifies the include a deblocking modeindicator for a video region indicative of applicability of adeblocking_filter to the video region during the conversion.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video comprisingone or more video pictures comprising one or more video slices and/orone or more video subpictures and a coded representation of the video,wherein the coded representation conforms to a format rule thatspecifies that a flag indicating whether a single slice per subpicturemode is deemed to be enabled for a video picture in case that a picturepartitioning is disabled for the video picture.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video comprisingone or more video pictures comprising one or more video slices and acoded representation of the video, wherein the coded representationconforms to a format rule that specifies that a picture or a slice levelchroma quantization parameter offset is signaled in a picture header ora slice header.

In another example aspect, another video processing method is disclosed.The method includes: performing a conversion between a video comprisingone or more video pictures comprising one or more video slices and acoded representation of the video, wherein the coded representationconforms to a format rule that specifies that a chroma quantizationparameter (QP) table applicable for conversion of a video block of thevideo is derived as an XOR operation between(delta_qp_in_val_minus1[i][j]+1) and delta_qp_ diff_val[i][j], whereindelta_qp_in_val_minus1[i][j] specifies a delta value used to derive theinput coordinate of the j-th pivot point of the i-th chroma mappingtable and delta_qp_ diff_val[i][j] specifies a delta value used toderive the output coordinate of the j-th pivot point of the i-th chromaQP mapping table, where i and j are integers.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video comprising apicture and a bitstream of the video according to a format rule, andwherein the format rule specifies that a presence of a syntax element ina sequence parameter set that indicates a constrain on loop filteringacross subpicture boundaries is based on whether a number of subpicturesin the picture is greater than 1.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video comprisingone or more pictures and a bitstream of the video according to a formatrule, and wherein the format rule specifies how to infer a value of asyntax element that is not present, wherein the syntax element relatedto treating a subpicture as a picture for excluding in-loop filteringoperations.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video comprisingone or more video regions and a bitstream of the video according to aformat rule, and wherein the format rule specifies that a sequenceparameter set includes syntax elements that are related to parameters ofa deblocking filter applicable to a video region.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video comprisingone or more pictures comprising one or more slices and a bitstream ofthe video according to a format rule, wherein the format rule specifiesthat a luma quantization parameter delta information and/or a chromaquantization parameter offset is included in both a picture header and aslice header in case that a certain condition is met.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video comprisingone or more video pictures comprising one or more video slices and abitstream of the video according to a format rule, and wherein theformat rule specifies to include a flag indicating a presence ofmultiple sets of chroma quantization parameter tables in a sequenceparameter set.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video comprisingone or more video pictures comprising one or more video slices and abitstream of the video according to a format rule, and wherein theformat rule specifies that indication of multiple sets of chromaquantization parameter tables is disabled for a sequence due to thesequence not including a slice of a particular type.

In another example aspect, another video processing method is disclosed.The method includes making a determination, for a conversion between avideo region of a video and a bitstream of the video, about how paddingor clipping is performed for an inter-prediction process at a boundaryof the video region according to a rule; and performing the conversionbased on the determination; wherein the rule is based on at least two of(a) a type of the boundary, (b) a first parameter indicative of whethera wrap-around motion compensation is enabled, or (c) a second parameterindicating whether subpicture boundaries are treated as pictureboundaries.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video comprisingone or more pictures and a bitstream of the video according to a formatrule, wherein the format rule specifies that offsets for wrap aroundpadding or clipping for subpictures of a picture are specified at asubpicture level.

In another example aspect, another video processing method is disclosed.The method includes performing a conversion between a video comprisingone or more video regions and a bitstream of the video according to aformat rule, wherein the format rule specifies that a variable Xindicates whether B slice is allowed or used in a video region, andwherein the format rule further specifies that the variable X is basedon values of a reference picture list information present flag and/or afield indicating a number of entries in a reference picture list syntaxstructure.

In yet another example aspect, a video encoder apparatus is disclosed.The video encoder comprises a processor configured to implementabove-described methods.

In yet another example aspect, a video decoder apparatus is disclosed.The video decoder comprises a processor configured to implementabove-described methods.

In yet another example aspect, a computer readable medium having codestored thereon is disclose. The code embodies one of the methodsdescribed herein in the form of processor-executable code.

These and other features are described throughout the present document.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of an example video processing system.

FIG. 2 is a block diagram of a video processing apparatus.

FIG. 3 is a flowchart for an example method of video processing.

FIG. 4 is a block diagram that illustrates a video coding system inaccordance with some embodiments of the present disclosure.

FIG. 5 is a block diagram that illustrates an encoder in accordance withsome embodiments of the present disclosure.

FIG. 6 is a block diagram that illustrates a decoder in accordance withsome embodiments of the present disclosure.

FIGS. 7A to 7F show flowcharts for example methods of video processingbased on some implementations of the disclosed technology.

FIGS. 8A and 8B show flowcharts for example methods of video processingbased on some implementations of the disclosed technology.

FIG. 9 shows a flowchart for an example method of video processing basedon some implementations of the disclosed technology.

DETAILED DESCRIPTION

Section headings are used in the present document for ease ofunderstanding and do not limit the applicability of techniques andembodiments disclosed in each section only to that section. Furthermore,H.266 terminology is used in some description only for ease ofunderstanding and not for limiting scope of the disclosed techniques. Assuch, the techniques described herein are applicable to other videocodec protocols and designs also.

1. Overview

This document is related to video coding technologies. Specifically, itis about the syntax design of APS, deblocking, subpicture, and QP deltain video coding. The ideas may be applied individually or in variouscombination, to any video coding standard or non-standard video codecthat supports multi-layer video coding, e.g., the being-developedVersatile Video Coding (VVC).

2. Abbreviations

ALF Adaptive Loop Filter

APS Adaptation Parameter Set

AU Access Unit

AUD Access Unit Delimiter

AVC Advanced Video Coding

CB/Cb Blue Difference Chroma

CR/Cr Red Difference Chroma

CLVS Coded Layer Video Sequence

CPB Coded Picture Buffer

CRA Clean Random Access

CTB Coding Tree Block

CTU Coding Tree Unit

CU Coding Unit

CVS Coded Video Sequence

DPB Decoded Picture Buffer

DPS Decoding Parameter Set

EOB End Of Bitstream

EOS End Of Sequence

GDR Gradual Decoding Refresh

HEVC High Efficiency Video Coding

HRD Hypothetical Reference Decoder

ID Identifier

IDR Instantaneous Decoding Refresh

TRAP Intra Random Access Point

JEM Joint Exploration Model

LMCS Luma Mapping With Chroma Scaling

MCTS Motion-Constrained Tile Sets

MVP Motion Vector Prediction

NAL Network Abstraction Layer

NUT NAL Unit Type

OLS Output Layer Set

PH Picture Header

PPS Picture Parameter Set

PROF Prediction Refinement with Optical Flow

PTL Profile, Tier and Level

PU Picture Unit

QP Quantization Parameter

RADL Random Access Decodable Leading (Picture)

RASL Random Access Skipped Leading (Picture)

RB SP Raw Byte Sequence Payload

SAO Sample Adaptive Offset

SEI Supplemental Enhancement Information

SH Slice Header

SPS Sequence Parameter Set

SVC Scalable Video Coding

TMVP Temporal Motion Vector Prediction

VCL Video Coding Layer

VPS Video Parameter Set

VTM VVC Test Model

VUI Video Usability Information

VVC Versatile Video Coding

WP Weighted Prediction

Y Luminance

3. Initial Discussion

Video coding standards have evolved primarily through the development ofthe well-known International Telecommunication Union—TelecommunicationStandardization Sector (ITU-T) and International Organization forStandardization (ISO)/International Electrotechnical Commission (IEC)standards. The ITU-T produced H.261 and H.263, ISO/IEC produced MovingPicture Experts Group (MPEG)-1 and MPEG-4 Visual, and the twoorganizations jointly produced the H.262/MPEG-2 Video and H.264/MPEG-4Advanced Video Coding (AVC) and H.265/HEVC standards. Since H.262, thevideo coding standards are based on the hybrid video coding structurewherein temporal prediction plus transform coding are utilized. Toexplore the future video coding technologies beyond HEVC, the JointVideo Exploration Team (WET) was founded by Video Coding Experts Group(VCEG) and MPEG jointly in 2015. Since then, many new methods have beenadopted by JVET and put into the reference software named JointExploration Model (JEM). The JVET meeting is concurrently held onceevery quarter, and the new coding standard is targeting at 50% bitratereduction as compared to HEVC. The new video coding standard wasofficially named as Versatile Video Coding (VVC) in the April 2018 JVETmeeting, and the first version of VVC test model (VTM) was released atthat time. As there are continuous effort contributing to VVCstandardization, new coding techniques are being adopted to the VVCstandard in every JVET meeting. The VVC working draft and test model VTMare then updated after every meeting. The VVC project is now aiming fortechnical completion (FDIS) at the July 2020 meeting.

3.1. PPS Syntax and Semantics

In the latest VVC draft text, the PPS syntax and semantics are asfollows:

Descriptor pic_parameter_set_rbsp( ) {  pps_pic_parameter_set_id ue(v) pps_seq_parameter_set_id u(4)  mixed_nalu_types_in_pic_flag u(1) pic_width_in_luma_samples ue(v)  pic_height_in_luma_samples ue(v) pps_conformance_window_flag u(1)  if( pps_conformance_window_flag ) {  pps_conf_win_left_offset ue(v)   pps_conf_win_right_offset ue(v)  pps_conf_win_top_offset ue(v)   pps_conf_win_bottom_offset ue(v)  } scaling_window_explicit_signalling_flag u(1)  if(scaling_window_explicit_signalling_flag ) {   scaling_win_left_offsetue(v)   scaling_win_right_offset ue(v)   scaling_win_top_offset ue(v)  scaling_win_bottom_offset ue(v)  }  output_flag_present_flag u(1) subpic_id_mapping_in_pps_flag u(1)  if( subpic_id_mapping_in_pps_flag ){   pps_num_subpics_minus1 ue(v)   pps_subpic_id_len_minus1 ue(v)   for(i = 0; i <= pps_num_subpic_minus1; i++ )    pps_subpic_id[ i ] u(v)  } no_pic_partition_flag u(1)  if( !no_pic_partition_flag ) {  pps_log2_ctu_size_minus5 u(2)   num_exp_tile_columns_minus1 ue(v)  num_exp_tile_rows_minus1 ue(v)   for( i = 0; i <=num_exp_tile_columns_minus1; i++ )    tile_column_width_minus1[ i ]ue(v)   for( i = 0; i <= num_exp_tile_rows_minus1; i++ )   tile_row_height_minus1[ i ] ue(v)   if( NumTilesInPic > 1 )   rect_slice_flag u(1)   if( rect_slice_flag )   single_slice_per_subpic_flag u(1)   if( rect_slice_flag &&!single_slice_per_subpic_flag   ) {    num_slices_in_pic_minus1 ue(v)   if( num_slices_in_pic_minus1 > 0 )     tile_idx_delta_present_flagu(1)    for( i = 0; i < num_slices_in_pic_minus1; i++ ) {     if(NumTileColumns > 1 )      slice_width_in_tiles_minus1[ i ] ue(v)     if(NumTileRows > 1 &&       ( tile_idx_delta_present_flag || tileIdx %NumTileColumns = = 0 ) )      slice_height_in_tiles_minus1[ i ] ue(v)    if( slice_width_in_tiles_minus1[ i ] = = 0 &&      slice_height_in_tiles_minus1[ i ] = = 0 &&  RowHeight[SliceTopLeftTileIdx[ i ] / NumTileColumns ]  > 1 ) {     num_exp_slices_in_tile[ i ] ue(v)      for( j = 0; j <num_exp_slices_in_tile[ i ]; j++      )      exp_slice_height_in_ctus_minus1[ j ] ue(v)      i +=NumSlicesInTile[ i ] − 1     }     if( tile_idx_delta_present_flag && i< num_slices_in_pic_minus1 )      tile_idx_delta[ i ] se(v)    }   }  loop_filter_across_tiles_enabled_flag u(1)  loop_filter_across_slices_enabled_flag u(1)  } cabac_init_present_flag u(1)  for( i = 0; i < 2; i++ )  num_ref_idx_default_active_minus1[ i ] ue(v)  rpl1_idx_present_flagu(1)  init_qp_minus26 se(v)  cu_qp_delta_enabled_flag u(1) pps_chroma_tool_offsets_present_flag u(1)  if(pps_chroma_tool_offsets_present_flag ) {   pps_cb_qp_offset se(v)  pps_cr_qp_offset se(v)   pps_joint_cbcr_qp_offset_present_flag u(1)  if( pps_joint_cbcr_qp_offset_present_flag )   pps_joint_cbcr_qp_offset_value se(v)  pps_slice_chroma_qp_offsets_present_flag u(1)  pps_cu_chroma_qp_offset_list_enabled flag u(1)  }  if(pps_cu_chroma_qp_offset_list_enabled_flag ) {  chroma_qp_offset_list_len_minus1 ue(v)   for( i = 0; i <=chroma_qp_offset_list_len_minus1;   i++ ) {    cb_qp_offset_list[ i ]se(v)    cr_qp_offset_list[ i ] se(v)    if(pps_joint_cbcr_qp_offset_present_flag )     joint_cbcr_qp_offset_list[ i] se(v)   }  }  pps_weighted_pred_flag u(1)  pps_weighted_bipred_flagu(1)  deblocking_filter_control_present_flag u(1)  if(deblocking_filter_control_present_flag ) {  deblocking_filter_override_enabled_flag u(1)  pps_deblocking_filter_disabled_flag u(1)   if(!pps_deblocking_filter_disabled_flag ) {    pps_beta_offset_div2 se(v)   pps_tc_offset_div2 se(v)    pps_cb_beta_offset_div2 se(v)   pps_cb_tc_offset_div2 se(v)    pps_cr_beta_offset_div2 se(v)   pps_cr_tc_offset_div2 se(v)   }  }  rpl_info_in_ph_flag u(1)  if(deblocking_filter_override_enabled_flag )   dbf_info_in_ph_flag u(1) sao_info_in_ph_flag u(1)  alf_info_in_ph_flag u(1)  if( (pps_weighted_pred_flag || pps_weighted_bipred_flag ) &&rpl_info_in_ph_flag )   wp_info_in_ph_flag u(1) qp_delta_info_in_ph_flag u(1)  pps_ref_wraparound_enabled_flag u(1) if( pps_ref_wraparound_enabled_flag )   pps_ref_wraparound_offset ue(v) picture_header_extension_present_flag u(1) slice_header_extension_present_flag u(1)  pps_extension_flag u(1)  if(pps_extension_flag )   while( more_rbsp_data( ) )   pps_extension_data_flag u(1)  rbsp_trailing_bits( ) }

A PPS RBSP shall be available to the decoding process prior to it beingreferenced, included in at least one AU with TemporalId less than orequal to the TemporalId of the PPS NAL unit or provided through externalmeans. All PPS NAL units with a particular value ofpps_pic_parameter_set_id within a PU shall have the same content.pps_pic_parameter_set_id identifies the PPS for reference by othersyntax elements. The value of pps_pic_parameter_set_id shall be in therange of 0 to 63, inclusive. PPS NAL units, regardless of thenuh_layer_id values, share the same value space ofpps_pic_parameter_set_id.

Let ppsLayerId be the value of the nuh_layer_id of a particular PPS NALunit, and vclLayerId be the value of the nuhlayer_id of a particular VCLNAL unit. The particular VCL NAL unit shall not refer to the particularPPS NAL unit unless ppsLayerId is less than or equal to vclLayerId andthe layer with nuh_layer_id equal to ppsLayerId is included in at leastone OLS that includes the layer with nuh_layer_id equal to vclLayerId.

pps_seq_parameter_set_id specifies the value of sps_seqparameter_set_idfor the SPS. The value of pps_seqparameter_set_id shall be in the rangeof 0 to 15, inclusive. The value of pps_seq_parameter_set_id shall bethe same in all PPSs that are referred to by coded pictures in a CLVS.

mixed_nalu_types_in_pic_flag equal to 1 specifies that each picturereferring to the PPS has more than one VCL NAL unit, the VCL NAL unitsdo not have the same value of nal_unit_type, and the picture is not anIRAP picture. mixed_nalu_types_in_pic_flag equal to 0 specifies thateach picture referring to the PPS has one or more VCL NAL units and theVCL NAL units of each picture refering to the PPS have the same value ofnal_unit_type. When no_mixed_nalu_types_in_pic_constraint_flag is equalto 1, the value of mixed_nalu_types_in_pic_flag shall be equal to 0.

For each slice with a nal_unit_type value nalUnitTypeA in the range ofIDR_W_RADL to CRA_NUT, inclusive, in a picture picA that also containsone or more slices with another value of nal_unit_type (i.e., the valueof mixed_nalu_types_in_pic_flag for the picture picA is equal to 1), thefollowing applies:

-   -   The slice shall belong to a subpicture subpicA for which the        value of the corresponding subpic_treated_as_pic_flag[i] is        equal to 1.    -   The slice shall not belong to a subpicture of picA containing        VCL NAL units with nal_unit_type not equal to nalUnitTypeA.    -   If nalUnitTypeA is equal to CRA, for all the following PUs        following the current picture in the CLVS in decoding order and        in output order, neither RefPicList[0] nor RefPicList[1] of a        slice in subpicA in those PUs shall include any picture        preceding picA in decoding order in an active entry.    -   Otherwise (i.e., nalUnitTypeA is equal to IDR_W_RADL or        IDR_N_LP), for all the PUs in the CLVS following the current        picture in decoding order, neither RefPicList[0] nor        RefPicList[1] of a slice in subpicA in those PUs shall include        any picture preceding picA in decoding order in an active entry.    -   NOTE 1—mixed_nalu_types_in_pic_flag equal to 1 indicates that        pictures referring to the PPS contain slices with different NAL        unit types, e.g., coded pictures originating from a subpicture        bitstream merging operation for which encoders have to ensure        matching bitstream structure and further alignment of parameters        of the original bitstreams. One example of such alignments is as        follows: When the value of sps_idr_rpl_flag is equal to 0 and        mixednalu_types_in_pic_flag is equal to 1, a picture referring        to the PPS cannot have slices with nal_unit_type equal to        IDR_W_RADL or IDR_N_LP.

pic_width_in_lumasamples specifies the width of each decoded picturereferring to the PPS in units of luma samples. pic_width_in_luma_samplesshall not be equal to 0, shall be an integer multiple of Max(8,MinCbSizeY), and shall be less than or equal topic_width_max_in_luma_samples.

When res_change_in_clvs_allowed_flag equal to 0, the value ofpic_width_in_luma_samples shall be equal topic_width_max_in_luma_samples.

pic_height_in_lumasamples specifies the height of each decoded picturereferring to the PPS in units of luma samples.pic_height_in_luma_samples shall not be equal to 0 and shall be aninteger multiple of Max(8, MinCbSizeY), and shall be less than or equalto pic_height_max_inlumasamples.

When res_change_in_clvs_allowed_flag equal to 0, the value ofpic_height_in_luma_samples shall be equal topic_height_max_in_luma_samples.

The variables PicWidthlnCtbsY, PicHeightlnCtbsY, PicSizelnCtbsY,PicWidthlnMinCbsY, PicHeightlnMinCbsY, PicSizelnMinCbsY,PicSizelnSamplesY, PicWidthlnSamplesC and PicHeightlnSamplesC arederived as follows:

PicWidthInCtbsY=Ceil(pic_width_in_luma_samples÷CtbSizeY)   (69)

PicHeightlnCtbsY=Ceil(pic_height_in_luma_samples÷CtbSizeY)   (70)

PicSizelnCtbsY=PicWidthlnCtbsY * PicHeightlnCtbsY   (71)

PicWidthlnMinCbsY=pic_width_in_luma_samples/MinCbSizeY   (72)

PicHeightInMinCbsY=pic_height_in_luma_samples/MinCbSizeY   (73)

PicSizelnMinCbsY=PicWidthInMinCbsY * PicHeightlnMinCbsY   (74)

PicSizeInSamplesY=pic_width_in_luma_samples * pic_height_in_lumasamples  (75)

PicWidthlnSamplesC=pic_width_in_luma_samples/SubWidthC   (76)

PicHeightlnSamplesC=pic_height_in_luma_samples/SubHeightC   (77)

pps_conformance_window_flag equal to 1 indicates that the conformancecropping window offset parameters follow next in the PPS.pps_conformance_window_flag equal to 0 indicates that the conformancecropping window offset parameters are not present in the PPS.

pps_conf_win_left_offset, pps_conf_win_right_offset,pps_conf_win_top_offset, and pps_conf_win_bottom_offset specify thesamples of the pictures in the CLVS that are output from the decodingprocess, in terms of a rectangular region specified in picturecoordinates for output. When pps_conformance_window_flag is equal to 0,the values of pps_conf_winieft_offset, pps_conf_win_right_offset,pps_conf_win_top_offset, and pps_conf_win_bottom_offset are inferred tobe equal to 0.

The conformance cropping window contains the luma samples withhorizontal picture coordinates from SubWidthC * pps_conf_winieft_offsetto

pic_widthin_lumasamples—(SubWidthC * pps_conf_winright_offset+1) andvertical picture coordinates from SubHeightC * pps_conf_win_top_offsetto

pic_height_in_lumasamples—(SubHeightC * pps_conf_win_bottom_offset+1),inclusive. The value of SubWidthC *(pps_conf_winieft_offset+pps_conf_win_right_offset) shall be less thanpic_widthin_lumasamples, and the value of

SubHeightC * (pps_conf_win_top_offset+pps_conf_win_bottom_offset) shallbe less than pic_height_in_luma_samples.

When ChromaArrayType is not equal to 0, the corresponding specifiedsamples of the two chroma arrays are the samples having picturecoordinates (x/SubWidthC, y/SubHeightC), where (x, y) are the picturecoordinates of the specified luma samples.

-   -   NOTE 2—The conformance cropping window offset parameters are        only applied at the output. All internal decoding processes are        applied to the uncropped picture size.

Let ppsA and ppsB be any two PPSs referring to the same SPS. It is arequirement of bitstream conformance that, when ppsA and ppsB have thesame the values of pic_width_in_luma_samples andpic_height_in_luma_samples, respectively, ppsA and ppsB shall have thesame values of pps_conf_winieft_offset, pps_conf_win_right_offset,pps_conf_win_top_offset, and pps_conf_win_bottom_offset, respectively.

When pic_width_in_luma_samples is equal to pic_width_max_in_luma_samplesand pic_height_in_luma_samples is equal topic_height_max_inluma_samples, it is a requirement of bitstreamconformance that pps_conf_winieft_offset, pps_conf_win_right_offset,pps_conf_win_top_offset, and pps_conf_winbottom_offset, are equal tosps_conf_winieft_offset, sps_conf_win_right_offset,sps_conf_win_top_offset, and sps_conf_win_bottom_offset, respectively.

scaling_window_explicit_signalling_flag equal to 1 specifies that thescaling window offset parameters are present in the PPS.scaling_window_explicit_signalling_flag equal to 0 specifies that thescaling window offset parameters are not present in the PPS. Whenres_change_in_clvs_allowed_flag is equal to 0, the value ofscaling_window_explicit_signalling_flag shall be equal to 0.

scaling_win_left_offset, scaling_win_right_offset,scaling_win_top_offset, and scaling_win_bottom_offset specify theoffsets that are applied to the picture size for scaling ratiocalculation. When not present, the values of scaling_win_left_offset,scaling_win_right_offset, scaling_win_top_offset, andscaling_win_bottom_offset are inferred to be equal topps_conf_winieft_offset, pps_conf_win_right_offset,pps_conf_win_top_offset, and pps_conf_win_bottom_offset, respectively.

The value of SubWidthC *(scaling_win_left_offset+scaling_win_right_offset) shall be less thanpic_widthin_lumasamples, and the value of

SubHeightC * (scaling_win_top_offset+scaling_win_bottom_offset) shall beless than pic_height_in_luma_samples.

The variables PicOutputWidthL and PicOutputHeightL are derived asfollows:

PicOutputWidthL=pic_width_in_luma_samples−SubWidthC *(scaling_win_right_offset+scaling_win_left_offset)   (78)

PicOutputHeightL=pic_height_in_lumasamples−SubWidthC *(scaling_win_bottom_offset+scaling_win_top_offset)   (79)

Let refPicOutputWidthL and refPicOutputHeightL be the PicOutputWidthLand PicOutputHeightL, respectively, of a reference picture of a currentpicture referring to this PPS. Is a requirement of bitstream conformancethat all of the following conditions are satisfied:

-   -   PicOutputWidthL * 2 shall be greater than or equal to        refPicWidthInLumaSamples.    -   PicOutputHeightL * 2 shall be greater than or equal to        refPicHeightInLumaSamples.    -   PicOutputWidthL shall be less than or equal to        refPicWidthInLumaSamples * 8.    -   PicOutputHeightL shall be less than or equal to        refPicHeightInLumaSamples * 8.    -   PicOutputWidthL * pic_width_max_inlumasamples shall be greater        than or equal to refPicOutputWidthL *        (pic_widthin_lumasamples—Max(8, MinCbSizeY)).    -   PicOutputHeightL * pic_height_max_in_luma_samples shall be        greater than or equal to refPicOutputHeightL *        (pic_height_in_luma_samples—Max(8, MinCbSizeY)).

output_flag_present_flag equal to 1 indicates that the pic_output_flagsyntax element is present in slice headers referring to the PPS.output_flag_present_flag equal to 0 indicates that the pic_output_flagsyntax element is not present in slice headers referring to the PPS.

subpic_id_mapping_in_pps_flag equal to 1 specifies that the subpictureID mapping is signalled in the PPS. subpic_id_mapping_in_pps_flag equalto 0 specifies that the subpicture ID mapping is not signalled in thePPS. If subpic_id_mapping_explicitly_signalled_flag is 0 orsubpic_id_mapping_in_sps_flag is equal to 1, the value ofsubpic_id_mapping_in_pps_flag shall be equal to 0. Otherwise(subpic_id_mapping_explicitly_signalled_flag is equal to 1 andsubpic_id_mapping_in_sps_flag is equal to 0), the value ofsubpic_id_mapping_in_pps_flag shall be equal to 1.

pps_num_subpics_minus1 shall be equal to sps_num_subpics_minus1.

pps_subpic_id_len_minus1 shall be equal to sps_subpic_id_len_minus1.

pps_subpic_id[i] specifies the subpicture ID of the i-th subpicture. Thelength of the pps_subpic_id[i] syntax element ispps_subpic_id_len_minus1+1 bits.

The variable SubpicIdVal[i], for each value of i in the range of 0 tosps_num_subpics_minus1, inclusive, is derived as follows:

for( i = 0; i <= sps_num_subpics_minus1; i++ )  if(subpic_id_mapping_explicitly_signalled_flag )   SubpicIdVal[ i ] =subpic_id_mapping_in_pps_flag ?   pps_subpic_id[ i ] : sps_subpic_id[ i]  (80)  else   SubpicIdVal[ i ] = i

It is a requirement of bitstream conformance that both of the followingconstraints apply:

-   -   For any two different values of i and j in the range of 0 to        sps_num_subpics_minus1, inclusive, SubpicIdVal[i] shall not be        equal to SubpicIdVal[j].    -   When the current picture is not the first picture of the CLVS,        for each value of i in the range of 0 to sps_num_subpics_minus1,        inclusive, if the value of SubpicIdVal[i] is not equal to the        value of SubpicIdVal[i] of the previous picture in decoding        order in the same layer, the nal_unit_type for all coded slice        NAL units of the subpicture in the current picture with        subpicture index i shall be equal to a particular value in the        range of IDR_W_RADL to CRA_NUT, inclusive.

no_pic_partition_flag equal to 1 specifies that no picture partitioningis applied to each picture referring to the PPS. no_pic_partition_flagequal to 0 specifies each picture referring to the PPS may bepartitioned into more than one tile or slice.

It is a requirement of bitstream conformance that the value ofno_pic_partition_flag shall be the same for all PPSs that are referredto by coded pictures within a CLVS.

It is a requirement of bitstream conformance that the value ofno_pic_partition_flag shall not be equal to 1 when the value ofsps_num_subpics_minus1+1 is greater than 1.

pps_log2_ctu_size_minus5 plus 5 specifies the luma coding tree blocksize of each CTU. pps_log2_ctu_size_minus5 shall be equal tosps_log2_ctu_size_minus5.

num_exp_tile_columns_minus1 plus 1 specifies the number of explicitlyprovided tile column widths. The value of num_exp_tile_columns_minus 1shall be in the range of 0 to PicWidthlnCtbsY −1, inclusive. Whenno_pic_partition_flag is equal to 1, the value ofnum_exp_tile_columns_minus1 is inferred to be equal to 0.

num_exp_tile_rows_minus1 plus 1 specifies the number of explicitlyprovided tile row heights. The value of num_exp_tile_rows_minus 1 shallbe in the range of 0 to PicHeightlnCtbsY −1, inclusive. Whenno_pic_partition_flag is equal to 1, the value of num_tile_rows_minus1is inferred to be equal to 0.

tile_column_width_minus1[i] plus 1 specifies the width of the i-th tilecolumn in units of CTBs for i in the range of 0 tonum_exp_tile_columns_minus1 −1, inclusive.tile_column_width_minus1[num_exp_tile_columns_minus1 ] is used to derivethe width of the tile columns with index greater than or equal tonum_exp_tile_columns_minus1 as specified in clause 6.5.1. The value oftile_column_width_minus 1 [i] shall be in the range of 0 toPicWidthInCtbsY −1, inclusive. When not present, the value oftile_column_width_minus1[0] is inferred to be equal to PicWidthInCtbsY−1.

tile_row_height_minus1[i] plus 1 specifies the height of the i-th tilerow in units of CTBs for i in the range of 0 to num_exp_tile_rows_minus1−1, inclusive. tile_row_height_minus1[num_exp_tile_rows_minus1 ] is usedto derive the height of the tile rows with index greater than or equalto num_exp_tile_rows_minus 1 as specified in clause 6.5.1. The value oftile_row_height_minus1[i] shall be in the range of 0 to PicHeightInCtbsY−1, inclusive. When not present, the value of tile_row_height_minus1[0]is inferred to be equal to PicHeightlnCtbsY −1.

rect_slice_flag equal to 0 specifies that tiles within each slice are inraster scan order and the slice information is not signalled in PPS.rect_slice_flag equal to 1 specifies that tiles within each slice covera rectangular region of the picture and the slice information issignalled in the PPS. When not present, rect_slice_flag is inferred tobe equal to 1. When subpic_info_present_flag is equal to 1, the value ofrect_slice_flag shall be equal to 1.

single_slice_per_subpic_flag equal to 1 specifies that each subpictureconsists of one and only one rectangular slice.single_slice_per_subpic_flag equal to 0 specifies that each subpicturemay consist of one or more rectangular slices. Whensingle_slice_per_subpic_flag is equal to 1, num_slices_in_pic_minus 1 isinferred to be equal to sps_num_subpics_minus1. When not present, thevalue of single_slice_per_subpic_flag is inferred to be equal to 0.

num_slices_in_pic_minus1 plus 1 specifies the number of rectangularslices in each picture referring to the PPS. The value ofnum_slices_in_pic_minus1 shall be in the range of 0 toMaxSlicesPerPicture −1, inclusive, where MaxSlicesPerPicture isspecified in Annex A. When no_pic_partition_flag is equal to 1, thevalue of num_slices_in_pic_minus1 is inferred to be equal to 0.

tile_idx_delta_present_flag equal to 0 specifies that tile_idx_deltavalues are not present in the PPS and all rectangular slices in picturesreferring to the PPS are specified in raster order according to theprocess defined in clause 6.5.1. tile_idx_delta_present_flag equal to 1specifies that tile_idx_delta values may be present in the PPS and allrectangular slices in pictures referring to the PPS are specified in theorder indicated by the values of tile_idx_delta. When not present, thevalue of tile_idx_delta_present_flag is inferred to be equal to 0.

slice_width_in_tiles_minus1[i] plus 1 specifies the width of the i-threctangular slice in units of tile columns The value ofslice_width_in_tiles_minus1[i] shall be in the range of 0 toNumTileColumns −1, inclusive. When slice_width_in_tiles_minus1[i] is notpresent, the following applies:

-   -   If NumTileColumns is equal to 1, the value of        slice_width_in_tiles_minus1[i] is inferred to be equal to 0.    -   Otherwise, the value of slice_width_intiles_minus1[i] is        inferred as specified in clause 6.5.1.

slice_height_in_tiles_minus1[i] plus 1 specifies the height of the i-threctangular slice in units of tile rows. The value ofslice_height_in_tiles_minus1[i] shall be in the range of 0 toNumTileRows −1, inclusive. When slice_height_in_tiles_minus1[i] is notpresent, the following applies:

-   -   If NumTileRows is equal to 1, or tile_idx_delta_present_flag is        equal to 0 and tileldx % NumTileColumns is greater than 0), the        value of slice_height_in_tiles_minus1[i] is inferred to be equal        to 0.    -   Otherwise (NumTileRows is not equal to 1, and        tile_idx_delta_present_flag is equal to 1 or tileldx %        NumTileColumns is equal to 0), when tile_idx_delta_present_flag        is equal to 1 or tileldx % NumTileColumns is equal to 0, the        value of slice_height_in_tiles_minus1[i] is inferred to be equal        to slice_height_in_tiles_minus1[i−1].

num_exp_slices_in_tile[i] specifies the number of explicitly providedslice heights in the current tile that contains more than onerectangular slices. The value of num_exp_slices_in_file[i] shall be inthe range of 0 to RowHeight[tileY]−1, inclusive, where tileY is the tilerow index containing the i-th slice. When not present, the value ofnum_exp_slices_in_tile[i] is inferred to be equal to 0. Whennum_exp_slices_in_tile[i] is equal to 0, the value of the variableNumSlicesInTile[i] is derived to be equal to 1.

exp_slice_height_in_ctus_minus1[j] plus 1 specifies the height of thej-th rectangular slice in the current tile in units of CTU rows. Thevalue of exp_slice_height_in_ctus_minus1[j] shall be in the range of 0to RowHeight[tileY]−1, inclusive, where tileY is the tile row index ofthe current tile.

When num_exp_slices_in_tile[i] is greater than 0, the variableNumSlicesInTile[i] and SliceHeightInCtusMinus1[i+k] for k in the rangeof 0 to NumSlicesInTile[i]−1 are derived as follows:

remainingHeightInCtbsY = RowHeight[ SliceTopLeftTileIdx[ i ] /NumTileColumns ] numExpSliceInTile = num_exp_slices_in_tile[ i ] for( j= 0; j < numExpSliceInTile − 1; j++ ) {  SliceHeightInCtusMinus1[ i++ ]=  exp_slice_height_in_ctu_minus1[ j ]  remainingHeightInCtbsY −=SliceHeightInCtusMinus1[ j ] } uniformSliceHeightMinus1 =SliceHeightInCtusMinus1[ i − 1 ] (81) while( remainingHeightInCtbsY >=(uniformSliceHeightMinus1 + 1) ) {  SliceHeightInCtusMinus1[ i++ ] =uniformSliceHeightMinus1  remainingHeightInCtbsY −=(uniformSliceHeightMinus1 + 1)  j++ } if( remainingHeightInCtbsY > 0 ) { SliceHeightInCtusMinus1[ i++ ] = remainingHeightInCtbsY  j++ }NumSlicesInTile[ i ] = j

tile_idx_delta[i] specifies the difference between the tile index of thefirst tile in the i-th rectangular slice and the tile index of the firsttile in the (i+1)-th rectangular slice. The value of tile_idx_delta[i]shall be in the range of −NumTilesInPic+1 to NumTilesInPic −1,inclusive. When not present, the value of tile_idx_delta[i] is inferredto be equal to 0. When present, the value of tile_idx_delta[i] shall notbe equal to 0.

loop_filter_across_tlles_enabled_flag equal to 1 specifies that in-loopfiltering operations may be performed across tile boundaries in picturesreferring to the PPS. loop_filter_across_tiles_enabled_flag equal to 0specifies that in-loop filtering operations are not performed acrosstile boundaries in pictures referring to the PPS. The in-loop filteringoperations include the deblocking_filter, sample adaptive offset filter,and adaptive loop filter operations. When not present, the value ofloop_filter_across_tiles_enabled_flag is inferred to be equal to 1.

loop_filter_across_slices_enabled_flag equal to 1 specifies that in-loopfiltering operations may be performed across slice boundaries inpictures referring to the PPS. loop_filter_across_slice_enabled_flagequal to 0 specifies that in-loop filtering operations are not performedacross slice boundaries in pictures referring to the PPS. The in-loopfiltering operations include the deblocking_filter, sample adaptiveoffset filter, and adaptive loop filter operations. When not present,the value of loop_filter_across_slices_enabled_flag is inferred to beequal to 0.

cabac_init_present_flag equal to 1 specifies that cabac_init_flag ispresent in slice headers referring to the PPS. cabac_init_present_flagequal to 0 specifies that cabac_init_flag is not present in sliceheaders referring to the PPS.

num_ref_idx_default_active_minusn ii plus 1, when i is equal to 0,specifies the inferred value of the variable NumRefIdxActive[0] for P orB slices with num_ref_idx_active_override_flag equal to 0, and, when iis equal to 1, specifies the inferred value of NumRefIdxActive[1] for Bslices with num_ref_idx_active_override_flag equal to 0. The value ofnum_ref_idx_default_active_minus1[i] shall be in the range of 0 to 14,inclusive.

rpl1_idx_present_flag equal to 0 specifies that ref_pic_list_sps_flag[1]and ref_pic_list_idx[1] are not present in the PH syntax structures orthe slice headers for pictures referring to the PPS.rpl1_idx_present_flag equal to 1 specifies that ref_pic_list_sps_flag[1]and ref_pic_list_idx[1] may be present in the PH syntax structures orthe slice headers for pictures referring to the PPS.

init_qp_minus26 plus 26 specifies the initial value of SliceQp_(Y) foreach slice referring to the PPS. The initial value of SliceQp_(Y) ismodified at the picture level when a non-zero value of ph_qp_delta isdecoded or at the slice level when a non-zero value of slice_qp_delta isdecoded. The value of init_qp_minus26 shall be in the range of−(26+QpBdOffset) to +37, inclusive.

cu_qp_delta_enabled_flag equal to 1 specifies that theph_cu_qp_delta_subdiv_intra_slice and ph_cu_qp_delta_subdiv_inter_slicesyntax elements are present in PHs referring to the PPS andcu_qp_delta_abs may be present in the transform unit syntax.cu_qp_delta_enabled_flag equal to 0 specifies that theph_cu_qp_delta_subdiv_intra_slice and ph_cu_qp_delta_subdiv_inter_slicesyntax elements are not present in PHs referring to the PPS andcu_qp_delta_abs is not present in the transform unit syntax.

pps_chroma_tool_offsets_present_flag equal to 1 specifies that chromatool offsets related syntax elements are present in the PPS RB SP syntaxstructure. pps_chroma_tool_offsets_present_flag equal to 0 specifiesthat chroma tool offsets related syntax elements are not present in inthe PPS RBSP syntax structure. When ChromaArrayType is equal to 0, thevalue of pps_chroma_tool_offsets_present_flag shall be equal to 0.

pps_cb_qp_offset and pps_cr_qp_offset specify the offsets to the lumaquantization parameter Qp′_(Y) used for deriving Qp′_(Cb) and Qp′_(Cr),respectively. The values of pps_cb_qp_offset and pps_cr_qp_offset shallbe in the range of −12 to +12, inclusive. When ChromaArrayType is equalto 0, pps_cb_qp_offset and pps_cr_qp_offset are not used in the decodingprocess and decoders shall ignore their value. When not present, thevalues of pps_cb_qp_offset and pps_cr_qp_offset are inferred to beequalt to 0.

pps_joint_cbcr_qp_offset_present_flag equal to 1 specifies thatpps_joint_cbcr_qp_offset_value and joint_cbcr_qp_offset_list[i] arepresent in the PPS RBSP syntax structure.pps_joint_cbcr_qp_offset_present_flag equal to 0 specifies thatpps_joint_cbcr_qp_offset_value and joint_cbcr_qp_offset_list[i] are notpresent in the PPS RBSP syntax structure. When ChromaArrayType is equalto 0 or sps_joint_cbcr_enabled_flag is equal to 0, the value ofpps_joint_cbcr_qp_offset_present_flag shall be equal to 0. When notpresent, the value of pps_joint_cbcr_qp_offset_present_flag is inferredto be equal to 0.

pps_joint_cbcr_qp_offset_value specifies the offset to the lumaquantization parameter Qp′_(Y) used for deriving Qp′_(CbCr). The valueof pps_joint_cbcr_qp_offset_value shall be in the range of −12 to +12,inclusive. When ChromaArrayType is equal to 0 orsps_joint_cbcr_enabled_flag is equal to 0,pps_joint_cbcr_qp_offset_value is not used in the decoding process anddecoders shall ignore its value. Whenpps_joint_cbcr_qp_offset_present_flag is equal to 0,pps_joint_cbcr_qp_offset_value is not present and is inferred to beequal to 0.

pps_slice_chroma_qp_offsets_present_flag equal to 1 specifies that theslice_cb_qp_offset and slice_cr_qp_offset syntax elements are present inthe associated slice headers. pps_slice_chroma_qp_offsetspresent_flagequal to 0 specifies that the slice_cb_qp_offset and slice_cr_qp_offsetsyntax elements are not present in the associated slice headers. Whennot present, the value of pps_slice_chroma_qp_offsetspresent_flag isinferred to be equal to 0.

pps_cu_chroma_qp_offset_list_enabled_flag equal to 1 specifies that theph_cu_chroma_qp_offset_subdiv_intra_slice andph_cu_chroma_qp_offset_subdiv_inter_slice syntax elements are present inPHs referring to the PPS and cu_chroma_qp_offset_flag may be present inthe transform unit syntax and the palette coding syntax.pps_cu_chroma_qp_offset_list_enabled_flag equal to 0 specifies that theph_cu_chroma_qp_offset_subdiv_intra_slice andph_cu_chroma_qp_offset_subdiv_inter_slice syntax elements are notpresent in PHs referring to the PPS and the cu_chroma_qp_offset_flag isnot present in the transform unit syntax and the palette coding syntax.When not present, the value of pps_cu_chroma_qp_offset_list_enabled_flagis inferred to be equal to 0.

chroma_qp_offset_list_len_minus1 plus 1 specifies the number ofcb_qp_offset_list[i], cr_qp_offset_list[i], andjoint_cbcr_qp_offset_list[i], syntax elements that are present in thePPS RBSP syntax structure. The value of chroma_qp_offset_list_lenminus1shall be in the range of 0 to 5, inclusive.

cb_qp_offset_list[i], cr_qp_offset_list[i], andjoint_cbcr_qp_offset_list[i], specify offsets used in the derivation ofQp′_(Cb), Qp _(Cr), and Qp′_(CbCr), respectively. The values ofcb_qp_offset_list[i], cr_qp_offset_list[i], andjoint_cbcr_qp_offset_list[i] shall be in the range of −12 to +12,inclusive. When pps_joint_cbcr_qp_offset_present_flag is equal to 0,joint_cbcr_qp_offset_list[i] is not present and it is inferred to beequal to 0.

pps_weighted_pred_flag equal to 0 specifies that weighted prediction isnot applied to P slices referring to the PPS. pps_weighted_pred_flagequal to 1 specifies that weighted prediction is applied to P slicesreferring to the PPS. When sps_weighted_pred_flag is equal to 0, thevalue of pps_weighted_pred_flag shall be equal to 0.

pps_weighted_bipred_flag equal to 0 specifies that explicit weightedprediction is not applied to B slices referring to the PPS.pps_weighted_bipred_flag equal to 1 specifies that explicit weightedprediction is applied to B slices referring to the PPS. Whensps_weighted_bipred_flag is equal to 0, the value ofpps_weighted_bipred_flag shall be equal to 0.

deblocking_filter_control_present_flag equal to 1 specifies the presenceof deblocking_filter control syntax elements in the PPS.deblocking_filter_control_present_flag equal to 0 specifies the absenceof deblocking_filter control syntax elements in the PPS.

deblocking_filter_override_enabled_flag equal to 1 specifies thepresence of ph_deblocking_filter_override_flag in the PHs referring tothe PPS or slice_deblocking_filter_override_flag in the slice headersreferring to the PPS. deblocking_filter_override_enabled_flag equal to 0specifies the absence of ph_deblocking_filter_override_flag in PHsreferring to the PPS or slice_deblocking_filter_override_flag in sliceheaders referring to the PPS. When not present, the value ofdeblocking_filter_override_enabled_flag is inferred to be equal to 0.

pps_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of deblocking filter is not applied for slices referring tothe PPS in which slice_deblocking_filter_disabled_flag is not present.pps_deblocking_filter_disabled_flag equal to 0 specifies that theoperation of the deblocking filter is applied for slices referring tothe PPS in which slice_deblocking_filter_disabled_flag is not present.When not present, the value of pps_deblocking_filter_disabled_flag isinferred to be equal to 0.

pps_beta_offset_div2 and pps_tc_offset_div2 specify the defaultdeblocking parameter offsets for β and tC (divided by 2) that areapplied to the luma component for slices referring to the PPS, unlessthe default deblocking parameter offsets are overridden by thedeblocking parameter offsets present in the picture headers or the sliceheaders of the slices referring to the PPS. The values ofpps_beta_offset_div2 and pps_tc_offset_div2 shall both be in the rangeof −12 to 12, inclusive. When not present, the values ofpps_beta_offset_div2 and pps_tc_offset_div2 are both inferred to beequal to 0.

pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2 specify the defaultdeblocking parameter offsets for β and tC (divided by 2) that areapplied to the Cb component for slices referring to the PPS, unless thedefault deblocking parameter offsets are overridden by the deblockingparameter offsets present in the picture headers or the slice headers ofthe slices referring to the PPS. The values of pps_cb_beta_offset_div2and pps_cb_tc_offset_div2 shall both be in the range of −12 to 12,inclusive. When not present, the values of pps_cb_beta_offset_div2 andpps_cb_tc_offset_div2 are both inferred to be equal to 0.

pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2 specify the defaultdeblocking parameter offsets for β and tC (divided by 2) that areapplied to the Cr component for slices referring to the PPS, unless thedefault deblocking parameter offsets are overridden by the deblockingparameter offsets present in the picture headers or the slice headers ofthe slices referring to the PPS. The values of pps_cr_beta_offset_div2and pps_cr_tc_offset_div2 shall both be in the range of −12 to 12,inclusive. When not present, the values of pps_cr_beta_offset_div2 andpps_cr_tc_offset_div2 are both inferred to be equal to 0.

rpl_info_in_ph_flag equal to 1 specifies that reference picture listinformation is present in the PH syntax structure and not present inslice headers referring to the PPS that do not contain a PH syntaxstructure. rpl_info_in_ph_flag equal to 0 specifies that referencepicture list information is not present in the PH syntax structure andmay be present in slice headers referring to the PPS that do not containa PH syntax structure.

dbf_info_in_ph_flag equal to 1 specifies that deblocking_filterinformation is present in the PH syntax structure and not present inslice headers referring to the PPS that do not contain a PH syntaxstructure. dbf_info_inph_flag equal to 0 specifies thatdeblocking_filter information is not present in the PH syntax structureand may be present in slice headers referring to the PPS that do notcontain a PH syntax structure. When not present, the value ofdbf_info_inph_flag is inferred to be equal to 0.

sao_info_in_ph_flag equal to 1 specifies that SAO filter information ispresent in the PH syntax structure and not present in slice headersreferring to the PPS that do not contain a PH syntax structure.sao_info_inph_flag equal to 0 specifies that SAO filter information isnot present in the PH syntax structure and may be present in sliceheaders referring to the PPS that do not contain a PH syntax structure.

alf_info_in_ph_flag equal to 1 specifies that ALF information is presentin the PH syntax structure and not present in slice headers referring tothe PPS that do not contain a PH syntax structure. alf_info_inph_flagequal to 0 specifies that ALF information is not present in the PHsyntax structure and may be present in slice headers referring to thePPS that do not contain a PH syntax structure.

wp_info_in_ph_flag equal to 1 specifies that weighted predictioninformation may be present in the PH syntax structure and not present inslice headers referring to the PPS that do not contain a PH syntaxstructure. wp_info_inph_flag equal to 0 specifies that weightedprediction information is not present in the PH syntax structure and maybe present in slice headers referring to the PPS that do not contain aPH syntax structure. When not present, the value of wp_info_inph_flag isinferred to be equal to 0.

qp_delta_info_in_ph_flag equal to 1 specifies that QP delta informationis present in the PH syntax structure and not present in slice headersreferring to the PPS that do not contain a PH syntax structure.qp_delta_info_inph_flag equal to 0 specifies that QP delta informationis not present in the PH syntax structure and may be present in sliceheaders referring to the PPS that do not contain a PH syntax structure.

pps_ref wraparound_enabled_flag equal to 1 specifies that horizontalwrap-around motion compensation is applied in inter prediction. pps_refwraparound_enabled_flag equal to 0 specifies that horizontal wrap-aroundmotion compensation is not applied. When the value ofCtbSizeY/MinCbSizeY+1 is greater thanpic_width_in_luma_samples/MinCbSizeY −1, the value of pps_refwraparound_enabled_flag shall be equal to 0. When sps_refwraparound_enabled_flag is equal to 0, the value of pps_refwraparound_enabled_flag shall be equal to 0.

pps_ref wraparound_offset plus (CtbSizeY/MinCbSizeY)+2 specifies theoffset used for computing the horizontal wrap-around position in unitsof MinCbSizeY luma samples. The value of pps_ref wraparound_offset shallbe in the range of 0 to(pic_width_in_luma_samples/MinCbSizeY)−(CtbSizeY/MinCbSizeY)—2,inclusive. The variable PpsRefWraparoundOffset is set equal to pps_refwraparound_offset+(CtbSizeY/MinCbSizeY)+2.

picture_header_extension_present_flag equal to 0 specifies that no PHextension syntax elements are present in PHs referring to the PPS.picture_header_extension_present_flag equal to 1 specifies that PHextension syntax elements are present in PHs referring to the PPS.picture_header_extension_present_flag shall be equal to 0 in bitstreamsconforming to this version of this Specification.

slice_header_extension_present_flag equal to 0 specifies that no sliceheader extension syntax elements are present in the slice headers forcoded pictures referring to the PPS. slice_header_extension_present_flagequal to 1 specifies that slice header extension syntax elements arepresent in the slice headers for coded pictures referring to the PPS.slice_header_extension_present_flag shall be equal to 0 in bitstreamsconforming to this version of this Specification.

pps_extension_flag equal to 0 specifies that no pps_extension_data_flagsyntax elements are present in the PPS RBSP syntax structure.pps_extension_flag equal to 1 specifies that there arepps_extension_data_flag syntax elements present in the PPS RBSP syntaxstructure.

pps_extension_data_flag may have any value. Its presence and value donot affect decoder conformance to profiles specified in this version ofthis Specification. Decoders conforming to this version of thisSpecification shall ignore all pps_extension_data_flag syntax elements.

3.2. APS Syntax and Semantics

In the latest VVC draft text, the APS syntax and semantics are asfollows:

Descriptor adaptation_parameter_set_rbsp( ) { adaptation_parameter_set_id u(5)  aps_params_type u(3)  if(aps_params_type = = ALF_APS )   alf_data( )  else if( aps_params_type == LMCS_APS )   lmcs_data( )  else if( aps_params_type = = SCALING_APS )  scaling_list_data( )  aps_extension_flag u(1)  if( aps_extension_flag)   while( more_rbsp_data( ) )    aps_extension_data_flag u(1) rbsp_trailing_bits( ) }

The APS RBSP contains a ALF syntax structure, i.e., alf_data( )

Descriptor alf_data( ) {  alf_luma_filter_signal_flag u(1) alf_chroma_filter_signal_flag u(1)  alf_cc_cb_filter_signal_flag u(1) alf_cc_cr_filter_signal_flag u(1)  if( alf_luma_filter_signal_flag ) {  alf_luma_clip_flag u(1)   alf_luma_num_filters_signalled_minus1 ue(v)  if( alf_luma_num_filters_signalled_minus1 > 0 )    for( filtIdx = 0;filtIdx < NumAlfFilters; filtIdx++ )     alf_luma_coeff_delta_idx[filtIdx ] u(v)   for( sfIdx = 0; sfIdx <=  alf_luma_num_filters_signalled_minus1; sfIdx++ )    for( j = 0; j <12; j++ ) {     alf_luma_coeff_abs[ sfIdx ][ j ] ue(v)     if(alf_luma_coeff_abs[ sfIdx ][ j ] )      alf_luma_coeff_sign[ sfIdx ][ j] u(1)    }   if( alf_luma_clip_flag )    for( sfIdx = 0; sfIdx <=alf_luma_num_filters_signalled_minus1; sfIdx++ )     for( j = 0; j < 12;j++ )      alf_luma_clip_idx[ sfIdx ][ j ] u(2)  }  if(alf_chroma_filter_signal_flag ) {   alf_chroma_clip_flag u(1)  alf_chroma_num_alt_filters_minus1 ue(v)   for( altIdx = 0; altIdx <=  alf_chroma_num_alt_filters_minus1; altIdx++ ) {    for( j = 0; j < 6;j++ ) {     alf_chroma_coeff_abs[ altIdx ][ j ] ue(v)     if(alf_chroma_coeff_abs[ altIdx ][ j ] > 0 )      alf_chroma_coeff_sign[altIdx ][ j ] u(1)    }    if( alf_chroma_clip_flag )     for( j = 0; j< 6; j++ )      alf_chroma_clip_idx[ altIdx ][ j ] u(2)   }  }  if(alf_cc_cb_filter_signal_flag ) {   alf_cc_cb_filters_signalled_minus1ue(v)   for( k = 0; k < alf_cc_cb_filters_signalled_minus1 +   1; k++ ){    for( j = 0; j < 7; j++ ) {     alf_cc_cb_mapped_coeff_abs[ k ][ j ]u(3)     if( alf_cc_cb_mapped_coeff_abs[ k ][ j ] )     alf_cc_cb_coeff_sign[ k ][ j ] u(1)    }   }  }  if(alf_cc_cr_filter_signal_flag ) {   alf_cc_cr_filters_signalled_minus1ue(v)   for( k = 0; k < alf_cc_cr_filters_signalled_minus1 +   1; k++ ){    for( j = 0; j < 7; j++ ) {     alf_cc_cr_mapped_coeff_abs[ k ][ j ]u(3)     if( alf_cc_cr_mapped_coeff_abs[ k ][ j ] )     alf_cc_cr_coeff_sign[ k ][ j ] u(1)    }   }  } }

The APS RBSP contains a LMCS syntax structure, i.e., lmcs_data( )

Descriptor lmcs_data( ) {  lmcs_min_bin_idx ue(v) lmcs_delta_max_bin_idx ue(v)  lmcs_delta_cw_prec_minus1 ue(v)  for( i =lmcs_min_bin_idx; i <= LmcsMaxBinIdx; i++ ) {   lmcs_delta_abs_cw[ i ]u(v)   if( lmcs_delta_abs_cw[ i ] > 0 )    lmcs_delta_sign_cw_flag[ i ]u(1)  }  lmcs_delta_abs_crs u(3)  if( lmcs_delta_abs_crs > 0 )  lmcs_delta_sign_crs_flag u(1) }

The APS RBSP contains a scaling_list data syntax structure, i.e.,scaling_list_data( )

Descriptor scaling_list_data( ) {  scaling _(—) matrix _(—) for _(—)lfnst _(—) disabled _(—) flag u(1)  scaling _(—) list _(—) chroma _(—)present _(—) flag u(1)  for( id = 0; id < 28; id ++ )   matrixSize = (id< 2 ) ? 2 : ( ( id < 8 ) ? 4 : 8 )   if(scaling_list_chroma_present_flag | | ( id % 3 = = 2 ) | | ( id = = 27 )) {    scaling _(—) list _(—) copy _(—) mode _(—) flag[ id ] u(1)    if(!scaling_list_copy_mode_flag[ id ] )     scaling _(—) list _(—) pred_(—) mode _(—) flag[ id ] u(1)    if( ( scaling_list_copy_mode_flag[ id] | | scaling_list_pred_mode_flag[ id ] ) &&      id != 0 && id != 2 &&id != 8 )     scaling _(—) list _(—) pred _(—) id _(—) delta[ id ] ue(v)   if( !scaling_list_copy_mode_flag[ id ] ) {     nextCoef = 0     if(id > 13 ) {      scaling _(—) list _(—) dc _(—) coef[ id − 14 ] se(v)     nextCoef += scaling_list_dc_coef[ id − 14 ]     }     for( i = 0; i< matrixSize * matrixSize; i++ ) {      x = DiagScanOrder[ 3 ][ 3 ][ i][ 0 ]      y = DiagScanOrder[ 3 ][ 3 ][ i ][ 1 ]      if( !( id > 25 &&x >= 4 && y >= 4 ) ) {       scaling _(—) list _(—) delta _(—) coef[ id][ i ] se(v)       nextCoef += scaling_list_delta_coef[ id ][ i ]      }     ScalingList[ id ][ i ] = nextCoef     }    }   }  } }

Each APS RBSP shall be available to the decoding process prior to itbeing referenced, included in at least one AU with TemporalId less thanor equal to the TemporalId of the coded slice NAL unit that refers it orprovided through external means.

All APS NAL units with a particular value of adaptation_parameter_set_idand a particular value of aps_params_type within a PU, regardless ofwhether they are prefix or suffix APS NAL units, shall have the samecontent.

adaptation_parameter_set_id provides an identifier for the APS forreference by other syntax elements. When aps_params_type is equal toALF_APS or SCALING_APS, the value of adaptation_parameter_set_id shallbe in the range of 0 to 7, inclusive.

When aps_params_type is equal to LMCS_APS, the value ofadaptation_parameter_set_id shall be in the range of 0 to 3, inclusive.

Let apsLayerId be the value of the nuh_layer_id of a particular APS NALunit, and vclLayerId be the value of the nuh_layer_id of a particularVCL NAL unit. The particular VCL NAL unit shall not refer to theparticular APS NAL unit unless apsLayerId is less than or equal tovclLayerId and the layer with nuh_layer_id equal to apsLayerId isincluded in at least one OLS that includes the layer with nuh_layer_idequal to vclLayerId.

aps_params_type specifies the type of APS parameters carried in the APSas specified in Table 6.

TABLE 6 APS parameters type codes and types of APS parameters Name ofaps_params_type aps_params_type Type of APS parameters 0 ALF_APS ALFparameters 1 LMCS_APS LMCS parameters 2 SCALING_APS Scaling listparameters 3 . . . 7 Reserved Reserved

All APS NAL units with a particular value of aps_params_type, regardlessof the nuh_layer_id values, share the same value space foradaptation_parameter_set_id. APS NAL units with different values ofaps_params_type use separate values spaces foradaptation_parameter_set_id.

-   -   NOTE 1—An APS NAL unit (with a particular value of        adaptation_parameter_set_id and a particular value of        aps_params_type) can be shared across pictures, and different        slices within a picture can refer to different ALF APSs.    -   NOTE 2—A suffix APS NAL unit associated with a particular VCL        NAL unit (this VCL NAL unit precedes the suffix APS NAL unit in        decoding order) is not for use by the particular VCL NAL unit,        but for use by VCL NAL units following the suffix APS NAL unit        in decoding order.

aps_extension_flag equal to 0 specifies that no aps_extension_data_flagsyntax elements are present in the APS RBSP syntax structure.aps_extension_flag equal to 1 specifies that there areaps_extension_data_flag syntax elements present in the APS RBSP syntaxstructure.

aps_extension_data_flag may have any value. Its presence and value donot affect decoder conformance to profiles specified in this version ofthis Specification. Decoders conforming to this version of thisSpecification shall ignore all aps_extension_data_flag syntax elements.

alf_luma_filter_signal_flag equal to 1 specifies that a luma filter setis signalled. alf_luma_filter_signal_flag equal to 0 specifies that aluma filter set is not signalled.

alf_chroma_filter_signal_flag equal to 1 specifies that a chroma filteris signalled. alf_chroma_filter_signal_flag equal to 0 specifies that achroma filter is not signalled. When ChromaArrayType is equal to 0,alf_chroma_filter_signal_flag shall be equal to 0.

At least one of the values of alf_luma_filter_signal_flag,alf_chroma_filter_signal_flag, alf_cc_cb_filter_signal_flag andalf_cc_crfilter_signal_flag shall be equal to 1.

The variable NumAlfFilters specifying the number of different adaptiveloop filters is set equal to 25.

alf_luma_clip_flag equal to 0 specifies that linear adaptive loopfiltering is applied on luma component. alf_lumaclip_flag equal to 1specifies that non-linear adaptive loop filtering may be applied on lumacomponent.

alf_luma_num_filters_signalled_minus1 plus 1 specifies the number ofadpative loop filter classes for which luma coefficients can besignalled. The value of alf_lumanum_filters_signalled_minus1 shall be inthe range of 0 to NumAlfFilters −1, inclusive.

alf_luma_coeff_delta_idx[filtIdx] specifies the indices of the signalledadaptive loop filter luma_coefficient deltas for the filter classindicated by filtIdx ranging from 0 to NumAlfFilters −1. Whenalf_luma_coeff_delta_idx[filtIdx] is not present, it is inferred to beequal to 0. The length of alf_luma_coeff_delta_idx[filtIdx] isCeil(Log2(alf_lumanumfilters_signalled_minus 1+1)) bits. The value ofalf_luma_coeff_delta_idx[filtIdx] shall be in the range of 0 toalf_lumanumfilters_signalled_minus 1, inclusive.

alf_luma_coeff_abs[sfIdx][j] specifies the absolute value of the j-thcoefficient of the signalled luma filter indicated by sfIdx. Whenalf_luma_coeff_abs[sfIdx][j] is not present, it is inferred to be equal0. The value of alf_luma_coeff_abs[sfIdx][j] shall be in the range of 0to 128, inclusive.

alf_luma_coeff_sign[sfIdx][j] specifies the sign of the j-thluma_coefficient of the filter indicated by sfIdx as follows:

-   -   If alf_luma_coeff_sign[sfIdx][j] is equal to 0, the        corresponding luma filter coefficient has a positive value.    -   Otherwise (alf_luma_coeff_sign[sfIdx][j] is equal to 1), the        corresponding luma filter coefficient has a negative value.

When alf_luma_coeff_sign[sfIdx][j] is not present, it is inferred to beequal to 0.

The variable filtCoeff[sfIdx][j] withsfIdx=0..alf_luma_num_filters_signalled_minus1, j=0.11 is initialized asfollows:

filtCoeff[sfIdx][j]=alf_luma_coeff_abs[sfIdx][j]*(1-2*alf_luma_coeff_sign[sfIdx][j])   (93)

The luma filter coefficients AlfCoeff_(L)[adaptation_parameter_set_id]with elements

AlfCoeff_(L)[adaptation_parameter_set_id][filtIdx][j], withfiltIdx=0..NumAlfFilters −1 and j=0.11 are derived as follows:

AlfCoeff_(L)[adaptation_parameter_set_id][filtIdx][j]=filtCoeff[alf_luma_coeff_delta_idx[filtIdx]][j]  (94)

The fixed filter coefficients AlfFixFiltCoeff[i][j] with i=0.64, j=0.11and the class to filter mapping AlfClassToFiltMap[m ][n] with m=0.15 andn=0.24 are derived as follows:

AlfFixFiltCoeff = (95)  {   { 0, 0, 2, −3, 1, −4, 1, 7, −1, 1, −1, 5}  { 0, 0, 0, 0, 0, −1, 0, 1, 0, 0, −1, 2}   { 0, 0, 0, 0, 0, 0, 0, 1, 0,0, 0, 0}   { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, −1, 1}   { 2, 2, −7, −3, 0,−5, 13, 22, 12, −3, −3, 17}   {−1, 0, 6, −8, 1, −5, 1, 23, 0, 2, −5, 10}  { 0, 0, −1, −1, 0, −1, 2, 1, 0, 0, −1, 4}   { 0, 0, 3, −11, 1, 0, −1,35, 5, 2, −9, 9}   { 0, 0, 8, −8, −2, −7, 4, 4, 2, 1, −1, 25}   { 0, 0,1, −1, 0, −3, 1, 3, −1, 1, −1, 3}   { 0, 0, 3, −3, 0, −6, 5, −1, 2, 1,−4, 21}   {−7, 1, 5, 4, −3, 5, 11, 13, 12, −8, 11, 12}   {−5, −3, 6, −2,−3, 8, 14, 15, 2, −7, 11, 16}   { 2, −1, −6, −5, −2, −2, 20, 14, −4, 0,−3, 25}   { 3, 1, −8, −4, 0, −8, 22, 5, −3, 2, −10, 29}   { 2, 1, −7,−1, 2, −11, 23, −5, 0, 2, −10, 29}   {−6, −3, 8, 9, −4, 8, 9, 7, 14, −2,8, 9}   { 2, 1, −4, −7, 0, −8, 17, 22, 1, −1, −4, 23}   { 3, 0, −5, −7,0, −7, 15, 18, −5, 0, −5, 27}   { 2, 0, 0, −7, 1, −10, 13, 13, −4, 2,−7, 24}   { 3, 3, −13, 4, −2, −5, 9, 21, 25, −2, −3, 12}   {−5, −2, 7,−3, −7, 9, 8, 9, 16, −2, 15, 12}   { 0, −1, 0, −7, −5, 4, 11, 11, 8, −6,12, 21}   { 3, −2, −3, −8, −4, −1, 16, 15, −2, −3, 3, 26}   { 2, 1, −5,−4, −1, −8, 16, 4, −2, 1, −7, 33}   { 2, 1, −4, −2, 1, −10, 17, −2, 0,2, −11, 33}   { 1, −2, 7, −15, −16, 10, 8, 8, 20, 11, 14, 11}   { 2, 2,3, −13, −13, 4, 8, 12, 2, −3, 16, 24}   { 1, 4, 0, −7, −8, −4, 9, 9, −2,−2, 8, 29}   { 1, 1, 2, −4, −1, −6, 6, 3, −1, −1, −3, 30}   {−7, 3, 2,10, −2, 3, 7, 11, 19, −7, 8, 10}   { 0, −2, −5, −3, −2, 4, 20, 15, −1,−3, −1, 22}   { 3, −1, −8, −4, −1, −4, 22, 8, −4, 2, −8, 28}   { 0, 3,−14, 3, 0, 1, 19, 17, 8, −3, −7, 20}   { 0, 2, −1, −8, 3, −6, 5, 21, 1,1, −9, 13}   {−4, −2, 8, 20, −2, 2, 3, 5, 21, 4, 6, 1}   { 2, −2, −3,−9, −4, 2, 14, 16, 3, −6, 8, 24}   { 2, 1, 5, −16, −7, 2, 3, 11, 15, −3,11, 22}   { 1, 2, 3, −11, −2, −5, 4, 8, 9, −3, −2, 26}   { 0, −1, 10,−9, −1, −8, 2, 3, 4, 0, 0, 29}   { 1, 2, 0, −5, 1, −9, 9, 3, 0, 1, −7,20}   {−2, 8, −6, −4, 3, −9, −8, 45, 14, 2, −13, 7}   { 1, −1, 16, −19,−8, −4, −3, 2, 19, 0, 4, 30}   { 1, 1, −3, 0, 2, −11, 15, −5, 1, 2, −9,24}   { 0, 1, −2, 0, 1, −4, 4, 0, 0, 1, −4, 7}   { 0, 1, 2, −5, 1, −6,4, 10, −2, 1, −4, 10}   { 3, 0, −3, −6, −2, −6, 14, 8, −1, −1, −3, 31}  { 0, 1, 0, −2, 1, −6, 5, 1, 0, 1, −5, 13}   { 3, 1, 9, −19, −21, 9, 7,6, 13, 5, 15, 21}   { 2, 4, 3, −12, −13, 1, 7, 8, 3, 0, 12, 26}   { 3,1, −8, −2, 0, −6, 18, 2, −2, 3, −10, 23}   { 1, 1, −4, −1, 1, −5, 8, 1,−1, 2, −5, 10}   { 0, 1, −1, 0, 0, −2, 2, 0, 0, 1, −2, 3}   { 1, 1, −2,−7, 1, −7, 14, 18, 0, 0, −7, 21}   { 0, 1, 0, −2, 0, −7, 8, 1, −2, 0,−3, 24}   { 0, 1, 1, −2, 2, −10, 10, 0, −2, 1, −7, 23}   { 0, 2, 2, −11,2, −4, −3, 39, 7, 1, −10, 9}   { 1, 0, 13, −16, −5, −6, −1, 8, 6, 0, 6,29}   { 1, 3, 1, −6, −4, −7, 9, 6, −3, −2, 3, 33}   { 4, 0, −17, −1, −1,5, 26, 8, −2, 3, −15, 30}   { 0, 1, −2, 0, 2, −8, 12, −6, 1, 1, −6, 16}  { 0, 0, 0, −1, 1, −4, 4, 0, 0, 0, −3, 11}   { 0, 1, 2, −8, 2, −6, 5,15, 0, 2, −7, 9}   { 1, −1, 12, −15, −7, −2, 3, 6, 6, −1, 7, 30}  },AlfClassToFiltMap = (96)  {   { 8, 2, 2, 2, 3, 4, 53, 9, 9, 52, 4, 4, 5,9, 2,  8, 10, 9, 1, 3, 39, 39, 10, 9, 52 }   { 11, 12, 13, 14, 15, 30,11, 17, 18, 19, 16, 20, 20, 4, 53,  21, 22, 23, 14, 25, 26, 26, 27, 28,10 }   { 16, 12, 31, 32, 14, 16, 30, 33, 53, 34, 35, 16, 20, 4, 7,  16,21, 36, 18, 19, 21, 26, 37, 38, 39 }   { 35, 11, 13, 14, 43, 35, 16, 4,34, 62, 35, 35, 30, 56, 7,  35, 21, 38, 24, 40, 16, 21, 48, 57, 39 }   {11, 31, 32, 43, 44, 16, 4, 17, 34, 45, 30, 20, 20, 7, 5,  21, 22, 46,40, 47, 26, 48, 63, 58, 10 }   { 12, 13, 50, 51, 52, 11, 17, 53, 45, 9,30, 4, 53, 19, 0,  22, 23, 25, 43, 44, 37, 27, 28, 10, 55 }   { 30, 33,62, 51, 44, 20, 41, 56, 34, 45, 20, 41, 41, 56, 5,  30, 56, 38, 40, 47,11, 37, 42, 57, 8 }   { 35, 11, 23, 32, 14, 35, 20, 4, 17, 18, 21, 20,20, 20, 4,  16, 21, 36, 46, 25, 41, 26, 48, 49, 58 }   { 12, 31, 59, 59,3, 33, 33, 59, 59, 52, 4, 33, 17, 59, 55,  22, 36, 59, 59, 60, 22, 36,59, 25, 55 }   { 31, 25, 15, 60, 60, 22, 17, 19, 55, 55, 20, 20, 53, 19,55,  22, 46, 25, 43, 60, 37, 28, 10, 55, 52 }   { 12, 31, 32, 50, 51,11, 33, 53, 19, 45, 16, 4, 4, 53, 5,  22, 36, 18, 25, 43, 26, 27, 27,28, 10 }   { 5, 2, 44, 52, 3, 4, 53, 45, 9, 3, 4, 56, 5, 0, 2,  5, 10,47, 52, 3, 63, 39, 10, 9, 52 }   { 12, 34, 44, 44, 3, 56, 56, 62, 45, 9,56, 56, 7, 5, 0,  22, 38, 40, 47, 52, 48, 57, 39, 10, 9 }   { 35, 11,23, 14, 51, 35, 20, 41, 56, 62, 16, 20, 41, 56, 7,  16, 21, 38, 24, 40,26, 26, 42, 57, 39 }   { 33, 34, 51, 51, 52, 41, 41, 34, 62, 0, 41, 41,56, 7, 5,  56, 38, 38, 40, 44, 37, 42, 57, 39, 10 }   { 16, 31, 32, 15,60, 30, 4, 17, 19, 25, 22, 20, 4, 53, 19,  21, 22, 46, 25, 55, 26, 48,63, 58, 55 }  },

It is a requirement of bitstream conformance that the values ofAlfCoeff_(L) [adaptation_parameter_set_id][filtIdx][j] withfiltIdx=0..NumAlfFilters −1, j=0.11 shall be in the range of −2⁷ to2⁷−1, inclusive.

alf_luma_clip_idx[sfIdx][j] specifies the clipping index of the clippingvalue to use before multiplying by the j-th coefficient of the signalledluma filter indicated by sfIdx. It is a requirement of bitstreamconformance that the values of alf_luma_clip_idx[sfIdx][j] withsfIdx=0..alf_luma_num_filters_signalled_minus 1 and j=0.11 shall be inthe range of 0 to 3, inclusive.

The luma filter clipping values AlfClip_(L)[adaptation_parameter_set_id]with elements AlfClip_(L)[adaptation_parameter_set_id][filtIdx][j], withfiltIdx=0..NumAlfFilters −1 and j=0.11 are derived as specified in Table8 depending on BitDepth and clipldx set equal toalf_luma_clip_idx[alf_luma_coeff_delta_idx[filtIdx]][j].

alf_chroma_clip_flag equal to 0 specifies that linear adaptive loopfiltering is applied on chroma components; alf_chroma_clip_flag equal to1 specifies that non-linear adaptive loop filtering is applied on chromacomponents. When not present, alf_chroma_clip_flag is inferred to beequal to 0.

alf_chroma_num_alt_filters_minus1 plus 1 specifies the number ofalternative filters for chroma components. The value ofalf_chroma_num_alt_filters_minus 1 shall be in the range of 0 to 7,inclusive.

alf_chroma_coeff_abs[altIdx][j] specifies the absolute value of the j-thchroma filter coefficient for the alternative chroma filter with indexaltIdx. When alf_chroma_coeff_abs[altIdx][j] is not present, it isinferred to be equal 0. The value of alf_chroma_coeff_abs[sfIdx][j]shall be in the range of 0 to 128, inclusive.

alf_chroma_coeff_sign[altIdx][j] specifies the sign of the j-th chromafilter coefficient for the alternative chroma filter with index altIdxas follows:

-   -   If alf_chroma_coeff_sign[altIdx][j] is equal to 0, the        corresponding chroma filter coefficient has a positive value.    -   Otherwise (alf_chroma_coeff_sign[altIdx][j] is equal to 1), the        corresponding chroma filter coefficient has a negative value.

When alf_chroma_coeff_sign[altIdx][j] is not present, it is inferred tobe equal to 0.

The chroma filter coefficientsAlfCoeff_(C)[adaptation_parameter_set_id][altIdx] with elementsAlfCoeff_(C)[adaptation_parameter_set_id][altIdx][j], withaltIdx=0..alf_chroma_num_alt_filters_minus1, j=0.5 are derived asfollows:

AlfCoeff_(C)[adaptation_parameter_set_id][altIdx][j]=alf_chroma_coeff_abs[altIdx][j]*(1−2*alf_chroma_coeff_sign[altIdx][j])   (97)

It is a requirement of bitstream conformance that the values ofAlfCoeffc[adaptation_parameter_set_id][altIdx][j] withaltIdx=0..alf_chroma_num_alt_filters_minus1, j=0.5 shall be in the rangeof −2⁷ to 2⁷−1, inclusive.

alf_cc_cb_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cb colour component are signalled.alf_cc_cb_filter_signal_flag equal to 0 specifies that cross-componentfilters for Cb colour component are not signalled. When ChromaArrayTypeis equal to 0, alf_cc_cb_filter_signal_flag shall be equal to 0.

alf_cc_cb_filters_signalled_minus1 plus 1 specifies the number ofcross-component filters for the Cb colour component signalled in thecurrent ALF APS. The value of alf_cc_cb_filters_signalled_minus1 shallbe in the range of 0 to 3, inclusive.

alf_cc_cb_mapped_coeff_abs[k][j] specifies the absolute value of thej-th mapped coefficient of the signalled k-th cross-component filter forthe Cb colour component. When alf_cc_cb_mapped_coeff_abs[k][j] is notpresent, it is inferred to be equal to 0.

alf_cc_cb_coeff_sign[k][j] specifies the sign of the j-th coefficient ofthe signalled k-th cross-component filter for the Cb colour component asfollows:

-   -   If alf_cc_cb_coeff_sign[k][j] is equal to 0, the corresponding        cross-component filter coefficient has a positive value.    -   Otherwise (alf_cc_cb_sign[k][j] is equal to 1), the        corresponding cross-component filter coefficient has a negative        value.

When alf_cc_cb_coeff_sign[k][j] is not present, it is inferred to beequal to 0.

The signalled k-th cross-component filter coefficients for the Cb colourcomponent

CcAlfApsCoeff_(Cb)[adaptation_parameter_set_id][k][j], with j=0.6 arederived as follows:

-   -   If alf_cc_cb_mapped_coeff_abs[k][j] is equal to 0,        CcAlfApsCoeff_(Cb)[adaptation_parameter_set_id][k][j] is set        equal to 0.    -   Otherwise, CcAlfApsCoeff_(Cb)[adaptation_parameter_set_id][k][j]        is set equal to (12* alf_cc_cb_coeff_sign[k][j]) *        2^(alf_cc_cb mapped_coeff_abs[k][j]−1).

alf_cc_cr_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cr colour component are signalled.alf_cc_cr_filter_signal_flag equal to 0 specifies that cross-componentfilters for the Cr colour component are not signalled. WhenChromaArrayType is equal to 0, alf_cc_cr_filter_signal_flag shall beequal to 0.

alf_cc_cr_filters_signalled_minus1 plus 1 specifies the number ofcross-component filters for the Cr colour component signalled in thecurrent ALF APS. The value of alf_cc_cr_filters_signalled_minus1 shallbe in the range of 0 to 3, inclusive.

alf_cc_cr_mapped coeff_abs[k][j] specifies the absolute value of thej-th mapped coefficient of the signalled k-th cross-component filter forthe Cr colour component. When alf_cc_cr_mapped coeff_abs[k][j] is notpresent, it is inferred to be equal to 0.

alf_cc_cr_coeff_sign[k][j] specifies the sign of the j-th coefficient ofthe signalled k-th cross-component filter for the Cr colour component asfollows:

-   -   If alf_cc_cr_coeff_sign[k][j] is equal to 0, the corresponding        cross-component filter coefficient has a positive value.    -   Otherwise (alf_cc_cr_sign[k][j] is equal to 1), the        corresponding cross-component filter coefficient has a negative        value.

When alf_cc_cr_coeff_sign[k][j] is not present, it is inferred to beequal to 0.

The signalled k-th cross-component filter coefficients for the Cr colourcomponent

CcAlfApsCoeff_(Cb)[adaptation_parameter_set_id][k][j], with j=0.6 arederived as follows:

-   -   If alf_cc_cr_mapped_coeff_abs[k][j] is equal to 0,        CcAlfApsCoeff_(Cr)[adaptation_parameter_set_id][k][j] is set        equal to 0.    -   Otherwise, CcAlfApsCoeff_(Cr)[adaptation_parameter_set_id][k][j]        is set equal to (1−2* alf_cc_cr_coeff_sign[k][j]) *        2^(alf_cc_cr_mapped_coeff_abs[k][j]−1).

alf_chroma_clip_idx[altIdx][j] specifies the clipping index of theclipping value to use before multiplying by the j-th coefficient of thealternative chroma filter with index altIdx. It is a requirement ofbitstream conformance that the values of alf_chroma_clip_idx[altIdx][j]with altIdx=0..alf_chroma_num_alt_filters_minus1, j=0.5 shall be in therange of 0 to 3, inclusive.

The chroma filter clipping valuesAlfClip_(C)[adaptation_parameter_set_id][altIdx] with elementsAlfClip_(C)[adaptation_parameter_set_id][altIdx][j], withaltIdx=0..alf_chroma_num_alt_filters_minus1, j=0.5 are derived asspecified in Table 8 depending on BitDepth and clipldx set equal toalf_chroma_clip_idx[altIdx][j].

TABLE 8 Specification AlfClip depending on BitDepth and clipIdx clipIdxBitDepth 0 1 2 3 8 2⁸  2⁵ 2³ 2¹ 9 2⁹  2⁶ 2⁴ 2² 10 2¹⁰ 2⁷ 2⁵ 2³ 11 2¹¹ 2⁸2⁶ 2⁴ 12 2¹² 2⁹ 2⁷ 2⁵ 13 2¹³  2¹⁰ 2⁸ 2⁶ 14 2¹⁴  2¹¹ 2⁹ 2⁷ 15 2¹⁵  2¹² 2¹⁰ 2⁸ 16 2¹⁶  2¹³  2¹¹ 2⁹

lmcs_min_bin_idx specifies the minimum bin index used in the lumamapping with chroma scaling construction process. The value oflmcs_min_bin_idx shall be in the range of 0 to 15, inclusive.

lmcs_delta_max_bin_idx specifies the delta value between 15 and themaximum bin index LmcsMaxBinIdx used in the luma mapping with chromascaling construction process. The value of lmcs_delta_max_bin_idx shallbe in the range of 0 to 15, inclusive. The value of LmcsMaxBinIdx is setequal to 15− lmcs_delta_max_bin_idx. The value of LmcsMaxBinIdx shall begreater than or equal to lmcs_min_bin_idx.

lmcs_delta_cw_prec_minus1 plus 1 specifies the number of bits used forthe representation of the syntax lmcs_delta_abs_cw[i]. The value oflmcs_delta_cw_prec_minus1 shall be in the range of 0 to BitDepth −2,inclusive.

lmcs_delta_abs_cw[i] specifies the absolute delta codeword value for theith bin.

lmcs_delta_sign_cw_flag[i] specifies the sign of the variablelmcsDeltaCW[i] as follows:

-   -   If lmcs_delta_sign_cw_flag[i] is equal to 0, lmcsDeltaCW[i] is a        positive value.    -   Otherwise (lmcs_delta_sign_cw_flag[i] is not equal to 0),        lmcsDeltaCW[i] is a negative value.

When lmcs_delta_sign_cw_flag[i] is not present, it is inferred to beequal to 0.

The variable OrgCW is derived as follows:

OrgCW=(1«BitDepth)/16  (98)

The variable lmcsDeltaCW[i], with i=lmcs_min_bin_idx..LmcsMaxBinIdx, isderived as follows:

lmcsDeltaCW[i]=(1−2* lmcs_delta_sign_cw_flag[i]*lmcs_delta_abs_cw[i]  (99)

The variable lmcsCW[i] is derived as follows:

-   -   For i=2.. lmcs_minbinidx −1, lmcsCW[i] is set equal 0.    -   For i=lmcs_min_bin_idx..LmcsMaxBinIdx, the following applies:

lmcsCW[i]=OrgCW+lmcsDeltaCW[i]  (100)

The value of lmcsCW[i] shall be in the range of (OrgCW»3) to(OrgCW«3-1), inclusive.

-   -   For i=LmcsMaxBinIdx+1.15, lmcsCW[i] is set equal 0.

It is a requirement of bitstream conformance that the followingcondition is true:

Σ_(i=0) ¹⁵lmcsCW[i] <=(1«BitDepth) −1   (101)

The variable InputPivot[i], with i=0.16, is derived as follows:

InputPivot[i]=i * OrgCW   (102)

The variable LmcsPivot[i] with i=0.16, the variables ScaleCoeff[i] andInvScaleCoeff[i] with i=0.15, are derived as follows:

LmcsPivot[ 0 ] = 0; for( i = 0; i <= 15; i++ ) {  LmcsPivot[ i + 1 ] =LmcsPivot[ i ] + lmcsCW[ i ]  ScaleCoeff[ i ] = ( lmcsCW[ i ] * (1 << 11) + ( 1 << ( Log2(  OrgCW ) − 1 ) ) ) >> ( Log2( OrgCW ) )  if( lmcsCW[i ] = = 0 ) (103)   InvScaleCoeff[ i ] = 0  else   InvScaleCoeff[ i ] =OrgCW * ( 1 << 11 ) / lmcsCW[ i ] }

It is a requirement of bitstream conformance that, fori=lmcs_minbin_idx..LmcsMaxBinIdx, when the value of LmcsPivot[i] is nota multiple of 1«(BitDepth −5), the value of (LmcsPivot[i]»(BitDepth −5))shall not be equal to the value of (LmcsPivot[i+1] »(BitDepth −5)).

lmcs_delta_abs_crs specifies the absolute codeword value of the variablelmcsDeltaCrs. The value of lmcs_delta_abs_crs shall be in the range of 0and 7, inclusive. When not present, lmcs_delta_abs_crs is inferred to beequal to 0.

lmcs_delta_sign_crs_flag specifies the sign of the variablelmcsDeltaCrs. When not present, lmcs_delta_sign_crs_flag is inferred tobe equal to 0.

The variable lmcsDeltaCrs is derived as follows:

lmcsDeltaCrs=(1-2* lmcs_delta_sign_crs_flag) * lmcs_delta_abs_crs  (104)

It is a requirement of bitstream conformance that, when lmcsCW[i] is notequal to 0, (lmcsCW[i]+lmcsDeltaCrs) shall be in the range of (OrgCW»3)to ((OrgCW«3) −1), inclusive. The variable ChromaScaleCoeff[i], with i=0. . . 15, is derived as follows:

if( lmcsCW[ i ] = = 0 )  ChromaScaleCoeff[ i ] = ( 1 << 11 ) else ChromaScaleCoeff[ i ] = OrgCW * ( 1 << 11 ) / ( lmcsCW[ i ] + lmcsDeltaCrs )

scaling_matrix_for_lfnst_disabled_flag equal to 1 specifies that scalingmatrices are not applied to blocks coded with LFNST.scaling_matrix_for_lfnst_disabled_flag equal to 0 specifies that thescaling matrices may apply to the blocks coded with LFNST.

scaling_list_chroma_present_flag equal to 1 specifies that chromascaling_lists are present in scaling_list_data( )scaling_list_chroma_present_flag equal to 0 specifies that chromascaling_lists are not present in scaling_list_data( ) It is arequirement of bitstream conformance thatscaling_list_chroma_present_flag shall be equal to 0 whenChromaArrayType is equal to 0, and shall be equal to 1 whenChromaArrayType is not equal to 0.

scaling_list_copy_mode_flag[id] equal to 1 specifies that the values ofthe scaling_list are the same as the values of a reference scaling_list.The reference scaling_list is specified byscaling_list_pred_id_delta[id]. scaling_list_copy_mode_flag[id] equal to0 specifies that scaling_list_pred_mode_flag is present.

scaling_list_pred_mode_flag[id] equal to 1 specifies that the values ofthe scaling_list can be predicted from a reference scaling_list. Thereference scaling_list is specified by scaling_list_pred_id_delta[id].scaling_list_pred_mode_flag[id] equal to 0 specifies that the values ofthe scaling_list are explicitly signalled. When not present, the valueof scaling_list_pred_mode_flag[id] is inferred to be equal to 0.

scaling_list_pred_id_deha [id] specifies the reference scaling_list usedto derive the predicted scaling matrix ScalingMatrixPred [id]. When notpresent, the value of scaling_list_pred_id_delta[id] is inferred to beequal to 0. The value of scaling_list_pred jd_delta[id] shall be in therange of 0 to maxIdDelta with maxIdDelta derived depending on id asfollows:

maxIdDelta=(id <2)? id:((id <8)? (id−2):(id−8))   (106)

The variables refId and matrixSize are derived as follows:

refId=id−scaling_list_pred_id_delta[id]  (107)

matrixSize=(id <2)? 2:((id <8)? 4 : 8)   (108)

The (matrixSize)x(matrixSize) array ScalingMatrixPred [x ][y ] withx=0..matrixSize −1, y=0..matrixSize −1 and the variableScalingMatrixDCPred are derived as follows:

-   -   When both scaling_list_copy_mode_flag[id] and        scaling_list_pred_mode_flag[id] are equal to 0, all elements of        ScalingMatrixPred are set equal to 8, and the value of        ScalingMatrixDCPred is set equal to 8.    -   Otherwise, when scaling_list_pred_id_delta[id] is equal to 0,        all elements of ScalingMatrixPred are set equal to 16, and        ScalingMatrixDCPred is set equal to 16.    -   Otherwise (either scaling_list_copy_mode_flag[id] or        scaling_list_pred_mode_flag[id] is equal to 1 and        scaling_list_pred_id_delta[id] is greater than 0),        ScalingMatrixPred is set equal to ScalingMatrixRec [refId], and        the following applies for ScalingMatrixDCPred:    -   If refId is greater than 13, ScalingMatrixDCPred is set equal to        ScalingMatrixDCRec[refId −14].    -   Otherwise (refId is less than or equal to 13),        ScalingMatrixDCPred is set equal to ScalingMatrixPred [0][0].

scaling_list_dc_coef[id −14] is used to derive the value of the variableScalingMatrixDC[id −14] when id is greater than 13 as follows:

ScalingMatrixDCRec[id −14]=(ScalingMatrixDCPred+scaling_list_dc_coef[id−14]) & 255   (109)

When not present, the value of scaling_list_dc_coef[id −14] is inferredto be equal to 0. The value of scaling_list_dc_coef[id −14] shall be inthe range of −128 to 127, inclusive. The value of ScalingMatrixDCRec[id−14] shall be greater than 0.

scaling_list_delta_coef[id][i] specifies the difference between thecurrent matrix coefficient ScalingList[id][i] and the previous matrixcoefficient ScalingList[id][i −1], when scaling_list_copy_mode_flag[id]is equal to 0. The value of scaling_list_delta_coef[id][i] shall be inthe range of −128 to 127, inclusive. Whenscaling_list_copy_mode_flag[id] is equal to 1, all elements ofScalingList[id] are set equal to 0. The (matrixSize)x(matrixSize) arrayScalingMatrixRec [id] is derived as follows:

ScalingMatrixRec[id][x][y]=(ScalingMatrixPred[x][y]+ScalingList[id][k])& 255 with k=0.. (matrixSize*matrixSize −1),   (110)

x=DiagScanOrder[Log2(matrixSize)][Log2(matrixSize)][k][0], and

y=DiagScanOrder[Log2(matrixSize)][Log2(matrixSize)][k][1]

The value of ScalingMatrixRec [id][x][y] shall be greater than 0.

3.3. PH Syntax and Semantics

In the latest VVC draft text, the PH syntax and semantics are asfollows:

Descriptor picture_header_rbsp( ) {  picture_header_structure( ) rbsp_trailing_bits( ) }

The PH RB SP contains a PH syntax structure, i.e., picture headerstructure( )

Descriptor picture_header_structure( ) {  gdr _(—) or _(—) irap _(—) pic_(—) flag u(1)  if( gdr_or_irap_pic_flag )   gdr _(—) pic _(—) flag u(1) ph _(—) inter _(—) slice _(—) allowed _(—) flag u(1)  if(ph_inter_slice_allowed_flag )   ph _(—) intra _(—) slice _(—) allowed_(—) flag u(1)  non _(—) reference _(—) picture _(—) flag u(1)  ph _(—)pic _(—) parameter _(—) set _(—) id ue(v)  ph _(—) pic _(—) order _(—)cnt _(—) lsb u(v)  if( gdr_or_irap_pic_flag )   no _(—) output _(—) of_(—) prior _(—) pics _(—) flag u(1)  if( gdr_pic_flag )   recovery _(—)poc _(—) cnt ue(v)  for( i = 0; i < NumExtraPhBits; i++ )   ph _(—)extra _(—) bit[ i ] u(1)  if( sps_poc_msb_flag ) {   ph _(—) poc _(—)msb _(—) present _(—) flag u(1)   if( ph_poc_msb_present_flag )    poc_(—) msb _(—) val u(v)  }  if( sps_alf_enabled_flag &&alf_info_in_ph_flag ) {   ph _(—) alf _(—) enabled _(—) flag u(1)   if(ph_alf_enabled_flag ) {    ph _(—) num _(—) alf _(—) aps _(—) ids _(—)luma u(3)    for( i = 0; i < ph_num_alf_aps_ids_luma; i++ )     ph _(—)alf _(—) aps _(—) id _(—) luma[ i ] u(3)    if( ChromaArrayType != 0 )    ph _(—) alf _(—) chroma _(—) idc u(2)    if( ph_alf_chroma_idc > 0 )    ph _(—) alf _(—) aps _(—) id _(—) chroma u(3)    if(sps_ccalf_enabled_flag ) {     ph _(—) cc _(—) alf _(—) cb _(—) enabled_(—) flag u(1)     if( ph_cc_alf_cb_enabled_flag )      ph _(—) cc _(—)alf _(—) cb _(—) aps _(—) id u(3)     ph _(—) cc _(—) alf _(—) cr _(—)enabled _(—) flag u(1)     if( ph_cc_alf_cr_enabled_flag )      ph _(—)cc _(—) alf _(—) cr _(—) aps _(—) id u(3)    }   }  }  if(sps_lmcs_enabled_flag ) {   ph _(—) lmcs _(—) enabled _(—) flag u(1)  if( ph_lmcs_enabled_flag ) {    ph _(—) lmcs _(—) aps _(—) id u(2)   if( ChromaArrayType != 0 )     ph _(—) chroma _(—) residual _(—)scale _(—) flag u(1)   }  }  if( sps_scaling_list_enabled_flag ) {   ph_(—) scaling _(—) list _(—) present _(—) flag u(1)   if(ph_scaling_list_present_flag )    ph _(—) scaling _(—) list _(—) aps_(—) id u(3)  }  if( sps_virtual_boundaries_enabled_flag &&!sps_virtual_boundaries_present_flag ) {   ph _(—) virtual _(—)boundaries _(—) present _(—) flag u(1)   if(ph_virtual_boundaries_present_flag ) {    ph _(—) num _(—) ver _(—)virtual _(—) boundaries u(2)    for( i = 0; i <ph_num_ver_virtual_boundaries; i++ )     ph _(—) virtual _(—) boundaries_(—) pos _(—) x[ i ] u(13)    ph _(—) num _(—) hor _(—) virtual _(—)boundaries u(2)    for( i = 0; i < ph_num_hor_virtual_boundaries; i++ )    ph _(—) virtual _(—) boundaries _(—) pos _(—) y[ i ] u(13)   }  } if( output_flag_present_flag )   pic _(—) output _(—) flag u(1)  if(rpl_info_in_ph_flag )   ref_pic_lists( )  if(partition_constraints_override_enabled_flag )   partition _(—)constraints _(—) override _(—) flag u(1)  if(ph_intra_slice_allowed_flag ) {   if(partition_constraints_override_flag ) {    ph _(—) log2 _(—) diff _(—)min _(—) qt _(—) min _(—) cb _(—) intra _(—) slice _(—) luma ue(v)    ph_(—) max _(—) mtt _(—) hierarchy _(—) depth _(—) intra _(—) slice _(—)luma ue(v)    if( ph_max_mtt_hierarchy_depth_intra_slice_luma != 0 ) {    ph _(—) log2 _(—) diff _(—) max _(—) bt _(—) min _(—) qt _(—) intra_(—) slice _(—) luma ue(v)     ph _(—) log2 _(—) diff _(—) max _(—) tt_(—) min _(—) qt _(—) intra _(—) slice _(—) luma ue(v)    }    if(qtbtt_dual_tree_intra_flag ) {     ph _(—) log2 _(—) diff _(—) min _(—)qt _(—) min _(—) cb _(—) intra _(—) slice _(—) chroma ue(v)     ph _(—)max _(—) mtt _(—) hierarchy _(—) depth _(—) intra _(—) slice _(—) chromaue(v)     if( ph_max_mtt_hierarchy_depth_intra_slice_chroma != 0 ) {  ph_(—) log2 _(—) diff _(—) max _(—) bt _(—) min _(—) qt _(—) intra _(—)slice _(—) chroma ue(v)  ph _(—) log2 _(—) diff _(—) max _(—) tt _(—)min _(—) qt _(—) intra _(—) slice _(—) chroma ue(v)     }    }   }  if(cu_qp_delta_enabled_flag )     ph _(—) cu _(—) qp _(—) delta _(—) subdiv_(—) intra _(—) slice ue(v)   if(pps_cu_chroma_qp_offset_list_enabled_flag )    ph _(—) cu _(—) chroma_(—) qp _(—) offset _(—) subdiv _(—) intra _(—) slice ue(v)  }  if(ph_inter_slice_allowed_flag ) {   if(partition_constraints_override_flag ) {    ph _(—) log2 _(—) diff _(—)min _(—) qt _(—) min _(—) cb _(—) inter _(—) slice ue(v)    ph _(—) max_(—) mtt _(—) hierarchy _(—) depth _(—) inter _(—) slice ue(v)    if(ph_max_mtt_hierarchy_depth_inter_slice != 0 ) {     ph _(—) log2 _(—)diff _(—) max _(—) bt _(—) min _(—) qt _(—) inter _(—) slice ue(v)    ph _(—) log2 _(—) diff _(—) max _(—) tt _(—) min _(—) qt _(—) inter_(—) slice ue(v)    }   }   if( cu_qp_delta_enabled_flag )    ph _(—) cu_(—) qp _(—) delta _(—) subdiv _(—) inter _(—) slice ue(v)   if(pps_cu_chroma_qp_offset_list_enabled_flag )    ph _(—) cu _(—) chroma_(—) qp _(—) offset _(—) subdiv _(—) inter _(—) slice ue(v)   if(sps_temporal_mvp_enabled_flag ) {    ph _(—) temporal _(—) mvp _(—)enabled _(—) flag u(1)    if( ph_temporal_mvp_enabled_flag &&rpl_info_in_ph_flag ) {     ph _(—) collocated _(—) from _(—) l0 _(—)flag u(1)     if( ( ph_collocated_from_l0_flag &&       num_ref_entries[0 ][ RplsIdx[ 0 ] ] > 1 ) | |       ( !ph_collocated_from_l0_flag &&      num_ref_entries[ 1 ][ RplsIdx[ 1 ] ] > 1 ) )      ph _(—)collocated _(—) ref _(—) idx ue(v)    }   }   mvd _(—) l1 _(—) zero _(—)flag u(1)   if( sps_fpel_mmvd_enabled_flag )    ph _(—) fpel _(—) mmvd_(—) enabled _(—) flag u(1)   if( sps_bdof_pic_present_flag )    ph _(—)disable _(—) bdof _(—) flag u(1)   if( sps_dmvr_pic_present_flag )    ph_(—) disable _(—) dmvr _(—) flag u(1)   if( sps_prof_pic_present_flag )   ph _(—) disable _(—) prof _(—) flag u(1)   if( (pps_weighted_pred_flag | | pps_weighted_bipred_flag ) &&wp_info_in_ph_flag )    pred_weight_table( )  }  if(qp_delta_info_in_ph_flag )   ph _(—) qp _(—) delta se(v)  if(sps_joint_cbcr_enabled_flag )   ph _(—) joint _(—) cbcr _(—) sign _(—)flag u(1)  if( sps_sao_enabled_flag && sao_info_in_ph_flag ) {   ph _(—)sao _(—) luma _(—) enabled _(—) flag u(1)   if( ChromaArrayType != 0 )   ph _(—) sao _(—) chroma _(—) enabled _(—) flag u(1)  }  if(sps_dep_quant_enabled_flag )   ph _(—) dep _(—) quant _(—) enabled _(—)flag u(1)  if( sps_sign_data_hiding_enabled_flag &&!ph_dep_quant_enabled_flag )   pic _(—) sign _(—) data _(—) hiding _(—)enabled _(—) flag u(1)  if( deblocking_filter_override_enabled_flag &&dbf_info_in_ph_flag ) {   ph _(—) deblocking _(—) filter _(—) override_(—) flag u(1)   if( ph_deblocking_filter_override_flag ) {    ph _(—)deblocking _(—) filter _(—) disabled _(—) flag u(1)    if(!ph_deblocking_filter_disabled_flag ) {     ph _(—) beta _(—) offset_(—) div2 se(v)     ph _(—) tc _(—) offset _(—) div2 se(v)     ph _(—)cb _(—) beta _(—) offset _(—) div2 se(v)     ph _(—) cb _(—) tc _(—)offset _(—) div2 se(v)     ph _(—) cr _(—) beta _(—) offset _(—) div2se(v)     ph _(—) cr _(—) tc _(—) offset _(—) div2 se(v)    }   }  } if( picture_header_extension_present_flag ) {   ph _(—) extension _(—)length ue(v)   for( i = 0; i < ph_extension_length; i++)    ph _(—)extension _(—) data _(—) byte[ i ] u(8)  } }

The PH syntax structure contains information that is common for allslices of the coded picture associated with the PH syntax structure.

gdr_or_irap_pic_flag equal to 1 specifies that the current picture is aGDR or IRAP picture. gdr_or_irap_pic_flag equal to 0 specifies that thecurrent picture may or may not be a GDR or IRAP picture.

gdr_pic_flag equal to 1 specifies the picture associated with the PH isa GDR picture. gdr_pic_flag equal to 0 specifies that the pictureassociated with the PH is not a GDR picture. When not present, the valueof gdr_pic_flag is inferred to be equal to 0. When gdr_enabled_flag isequal to 0, the value of gdr_pic_flag shall be equal to 0.

ph_inter_slice_allowed_flag equal to 0 specifies that all coded slicesof the picture have slice_type equal to 2. ph_inter_slice_allowed_flagequal to 1 specifies that there may or may not be one or more codedslices in the picture that have slice_type equal to 0 or 1.

ph_intra_slice_allowed_flag equal to 0 specifies that all coded slicesof the picture have slice_type equal to 0 or 1.ph_intra_slice_allowed_flag equal to 1 specifies that there may or maynot be one or more coded slices in the picture that have slice_typeequal to 2.When not present, the value of ph_intra_slice_allowed_flag isinferred to be equal to 1.

-   -   NOTE 1—For bitstreams that are suppposed to work subpicure based        bitstream merging without the need of changing PH NAL units, the        encoder is expected to set the values of both        ph_inter_slice_allowed_flag and ph_intra_slice_allowed_flag        equal to 1.

non_reference_picture_flag equal to 1 specifies the picture associatedwith the PH is never used as a reference picture.non_reference_picture_flag equal to 0 specifies the picture associatedwith the PH may or may not be used as a reference picture.

ph_pic_parameter_set_id specifies the value of pps_pic_parameter_set_idfor the PPS in use. The value of ph_pic_parameter_set_id shall be in therange of 0 to 63, inclusive.

It is a requirement of bitstream conformance that the value ofTemporalId of the PH shall be greater than or equal to the value ofTemporalId of the PPS that has pps_pic_parameter_set_id equal toph_pic_parameter_set_id.

ph_pic_order_cnt_lsb specifies the picture order count moduloMaxPicOrderCntLsb for the current picture. The length of theph_pic_order_cnt_lsb syntax element islog2_max_pic_order_cnt_lsb_minus4+4 bits. The value of theph_pic_order_cnt_lsb shall be in the range of 0 to MaxPicOrderCntLsb −1,inclusive.

no_output_of prior_pics_flag affects the output of previously-decodedpictures in the DPB after the decoding of a CLVSS picture that is notthe first picture in the bitstream as specified in Annex C.

recovery_poc_cnt specifies the recovery point of decoded pictures inoutput order. If the current picture is a GDR picture that is associatedwith the PH, and there is a picture picA that follows the current GDRpicture in decoding order in the CLVS that has PicOrderCntVal equal tothe PicOrderCntVal of the current GDR picture plus the value ofrecovery_poc_cnt, the picture picA is referred to as the recovery pointpicture. Otherwise, the first picture in output order that hasPicOrderCntVal greater than the PicOrderCntVal of the current pictureplus the value of recovery_poc_cnt is referred to as the recovery pointpicture. The recovery point picture shall not precede the current GDRpicture in decoding order. The value of recovery_poc_cnt shall be in therange of 0 to MaxPicOrderCntLsb −1, inclusive.

When the current picture is a GDR picture, the variable RpPicOrderCntValis derived as follows:

RpPicOrderCntVal=PicOrderCntVal+recovery_poc_cnt   (82)

NOTE 2—When gdr_enabled_flag is equal to 1 and PicOrderCntVal of thecurrent picture is greater than or equal to RpPicOrderCntVal of theassociated GDR picture, the current and subsequent decoded pictures inoutput order are exact match to the corresponding pictures produced bystarting the decoding process from the previous TRAP picture, whenpresent, preceding the associated GDR picture in decoding order.

ph_extra_bit[i] may be equal to 1 or 0. Decoders conforming to thisversion of this Specification shall ignore the value of ph_extra_bit[i].Its value does not affect decoder conformance to profiles specified inthis version of specification.

ph_poc_msb_present_flag equal to 1 specifies that the syntax elementpoc_msb_val is present in the PH. ph_poc_msb_present_flag equal to 0specifies that the syntax element poc_msb_val is not present in the PH.When vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is equalto 0 and there is a picture in the current AU in a reference layer ofthe current layer, the value of ph_poc_msb_present_flag shall be equalto 0.

poc_msb_val specifies the POC MSB value of the current picture. Thelength of the syntax element poc_msb_val is poc_msb_len_minus +1 bits.

ph_alf_enabled_flag equal to 1 specifies that adaptive loop filter isenabled for all slices associated with the PH and may be applied to Y,Cb, or Cr colour component in the slices. ph_alf_enabled_flag equal to 0specifies that adaptive loop filter may be disabled for one, or more, orall slices associated with the PH. When not present, ph_alf_enabled_flagis inferred to be equal to 0.

ph_num_alf_aps_ids_luma specifies the number of ALF APSs that the slicesassociated with the PH refers to.

ph_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of thei-th ALF APS that the luma component of the slices associated with thePH refers to.

The value of alf_luma_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto ph_alf_aps_id_luma[i] shall be equal to 1.

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i]shall be less than or equal to the TemporalId of the picture associatedwith the PH.

-   -   ph_alf_chroma_idc equal to 0 specifies that the adaptive loop        filter is not applied to Cb and Cr colour components.        ph_alf_chroma_idc equal to 1 indicates that the adaptive loop        filter is applied to the Cb colour component. ph_alf_chroma_idc        equal to 2 indicates that the adaptive loop filter is applied to        the Cr colour component. ph_alf_chroma_idc equal to 3 indicates        that the adaptive loop filter is applied to Cb and Cr colour        components. When ph_alf_chroma_idc is not present, it is        inferred to be equal to 0.    -   ph_alf_aps_id_chroma specifies the adaptation_parameter_set_id        of the ALF APS that the chroma component of the slices        associated with the PH refers to.    -   The value of alf_chroma_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to ph_alf_aps_id_chroma shall        be equal to 1.    -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        ph_alf_aps_id_chroma shall be less than or equal to the        TemporalId of the picture associated with the PH.    -   ph_cc_alf_cb_enabled_flag equal to 1 specifies that        cross-component filter for Cb colour component is enabled for        all slices associated with the PH and may be applied to Cb        colour component in the slices. ph_cc_alf_cb_enabled_flag equal        to 0 specifies that cross-component filter for Cb colour        component may be disabled for one, or more, or all slices        associated with the PH. When not present,        ph_cc_alf_cb_enabled_flag is inferred to be equal to 0.    -   ph_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id of        the ALF APS that the Cb colour component of the slices        associated with the PH refers to.

The value of alf_cc_cb_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto ph_cc_alf_cb_aps_id shall be equal to 1.

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal to ph_cc_alf_cb_aps_idshall be less than or equal to the TemporalId of the picture associatedwith the PH.

ph_cc_alf_cr_enabled_flag equal to 1 specifies that cross-compoentfilter for Cr colour component is enabled for all slices associated withthe PH and may be applied to Cr colour component in the slices.ph_cc_alf_cr_enabled_flag equal to 0 specifies that cross-componentfilter for Cr colour component may be disabled for one, or more, or allslices associated with the PH. When not present,ph_cc_alf_cr_enabled_flag is inferred to be equal to 0.

ph_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id of the ALFAPS that the Cr colour component of the slices associated with the PHrefers to.

The value of alf_cc_cr_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto ph_cc_alf_cr_aps_id shall be equal to 1.

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal to ph_cc_alf_cr_aps_idshall be less than or equal to the TemporalId of the picture associatedwith the PH.

ph_lmcs_enabled_flag equal to 1 specifies that luma mapping with chromascaling is enabled for all slices associated with the PH.ph_lmcs_enabled_flag equal to 0 specifies that luma mapping with chromascaling may be disabled for one, or more, or all slices associated withthe PH. When not present, the value of ph_lmcs_enabled_flag is inferredto be equal to 0.

ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the LMCS_APSthat the slices associated with the PH refers to. The TemporalId of theAPS NAL unit having aps_params_type equal to LMCS_APS andadaptation_parameter_set_id equal to ph_lmcs_aps_id shall be less thanor equal to the TemporalId of the picture associated with PH.

ph_chroma_residual_scale_flag equal to 1 specifies that chroma residualscaling is enabled for the all slices associated with the PH.ph_chroma_residual_scale_flag equal to 0 specifies that chroma residualscaling may be disabled for one, or more, or all slices associated withthe PH. When ph_chroma_residual_scale_flag is not present, it isinferred to be equal to 0.

ph_scaling_list_present_flag equal to 1 specifies that the scaling_listdata used for the slices associated with the PH is derived based on thescaling_list data contained in the referenced scaling_list APS.ph_scaling_list_present_flag equal to 0 specifies that the scaling_listdata used for the slices associated with the PH is set to be equal to16. When not present, the value of ph_scaling_list_present_flag isinferred to be equal to 0.

ph_scaling_list_aps_id specifies the adaptation_parameter_set_id of thescaling_list APS. The TemporalId of the APS NAL unit havingaps_params_type equal to SCALING_APS and adaptation_parameter_set_idequal to ph_scaling_list_aps_id shall be less than or equal to theTemporalId of the picture associated with PH.

ph_virtual_boundaries_present_flag equal to 1 specifies that informationof virtual boundaries is signalled in the PH.ph_virtual_boundaries_present_flag equal to 0 specifies that informationof virtual boundaries is not signalled in the PH. When there is one ormore than one virtual boundaries signalled in the PH, the in-loopfiltering operations are disabled across the virtual boundaries in thepicture. The in-loop filtering operations include the deblocking_filter,sample adaptive offset filter, and adaptive loop filter operations. Whennot present, the value of ph_virtual_boundaries_present_flag is inferredto be equal to 0.

It is a requirement of bitstream conformance that, whensubpic_info_present_flag is equal to 1, the value ofph_virtual_boundaries_present_flag shall be equal to 0.

The variable VirtualBoundariesPresentFlag is derived as follows:

VirtualBoundariesPresentFlag=0

if(sps_virtual_boundaries_enabled_flag)

VirtualBoundariesPresentFlag=sps_virtual_boundaries_present_flagph_virtual_boundaries_present_flag   (83)

ph_num_ver_virtual_boundaries specifies the number ofph_virtual_boundaries_pos_x[i] syntax elements that are present in thePH. When ph_num_ver_virtual_boundaries is not present, it is inferred tobe equal to 0. The variable NumVerVirtualBoundaries is derived asfollows:

NumVerVirtualBoundaries=0

if(sps_virtual_boundaries_enabled_flag)

NumVerVirtualBoundaries=sps_virtual_boundaries_present_flag?sps_num_ver_virtual_boundaries: ph_num_ver_virtual_boundaries   (84)

ph_virtual_boundaries_pos_x[i] specifies the location of the i-thvertical virtual boundary in units of luma samples divided by 8. Thevalue of ph_virtual_boundaries_pos_x[i] shall be in the range of 1 toCeil(pic_width_in_luma_samples÷8) −1, inclusive.

The list VirtualBoundariesPosX[i] for i ranging from 0 toNumVerVirtualBoundaries −1, inclusive, in units of luma samples,specifying the locations of the vertical virtual boundaries, is derivedas follows:

for(i=0;i<NumVerVirtualBoundaries; i++)

VirtualBoundariesPosX[i]=(sps_virtual_boundaries_present_flag?sps_virtual_boundaries_pos_x[i]: ph_virtual_boundaries_pos_x[i])* 8  (85)

The distance between any two vertical virtual boundaries shall begreater than or equal to CtbSizeY luma samples.

ph_num_hor_virtual_boundaries specifies the number ofph_virtual_boundaries_pos_y[i] syntax elements that are present in thePH. When ph_num_hor_virtual_boundaries is not present, it is inferred tobe equal to 0. The parameter NumHorVirtualBoundaries is derived asfollows:

NumHorVirtualBoundaries=0

if(sps_virtual_boundaries_enabled_flag)

NumHorVirtualBoundaries=sps_virtual_boundaries_present_flag?sps_num_hor_virtual_boundaries:ph_num_hor_virtual_boundaries   (86)

When sps_virtual_boundaries_enabled_flag is equal to 1 andph_virtual_boundaries_present_flag is equal to 1, the sum ofph_num_ver_virtual_boundaries and ph_num_hor_virtual_boundaries shall begreater than 0.

ph_virtual_boundaries_pos_y[i] specifies the location of the i-thhorizontal virtual boundary in units of luma samples divided by 8. Thevalue of ph_virtual_boundaries_pos_y[i] shall be in the range of 1 toCeil(pic_height_in_luma_samples ≥8) −1, inclusive.

The list VirtualBoundariesPosY[i] for i ranging from 0 toNumHorVirtualBoundaries −1, inclusive, in units of luma samples,specifying the locations of the horizontal virtual boundaries, isderived as follows:

for(i=0;i<NumHorVirtualBoundaries; i++)

VirtualBoundariesPosY[i]=(sps_virtual_boundaries_present_flag?sps_virtual_boundaries_pos_y[i]: ph_virtual_boundaries_pos_y[i]) * 8  (87)

The distance between any two horizontal virtual boundaries shall begreater than or equal to CtbSizeY luma samples.

pic_output_flag affects the decoded picture output and removal processesas specified in Annex C. When pic_output_flag is not present, it isinferred to be equal to 1.

partition_constraints_override_flag equal to 1 specifies that partitionconstraint parameters are present in the PH.partition_constraints_override_flag equal to 0 specifies that partitionconstraint parameters are not present in the PH. When not present, thevalue of partition_constraints_override_flag is inferred to be equal to0.

ph_log2_diff_min_qt_min_cb_intra_slice_luma specifies the differencebetween the base 2 logarithm of the minimum size in luma samples of aluma leaf block resulting from quadtree splitting of a CTU and the base2 logarithm of the minimum coding block size in luma samples for lumaCUs in the slices with slice_type equal to 2 (I) associated with the PH.The value of ph_log2_diff_min_qt_min_cb_intra_slice_luma shall be in therange of 0 to CtbLog2SizeY-MinCbLog2SizeY, inclusive. When not present,the value of ph_log2_diff_min_qt_min_cb_luma is inferred to be equal tosps_log2_diff_min_qt_min_cb_intra_slice_luma.

ph_max_mtt_hierarchy_depth_intra_slice_luma specifies the maximumhierarchy depth for coding units resulting from multi-type treesplitting of a quadtree leaf in slices with slice_type equal to 2 (I)associated with the PH. The value ofph_max_mtt_hierarchy_depth_intra_slice_luma shall be in the range of 0to 2*(CtbLog2SizeY-MinCbLog2SizeY), inclusive. When not present, thevalue of ph_max_mtt_hierarchy_depth_intra_slice_luma is inferred to beequal to sps_max_mtt_hierarchy_depth_intra_slice_luma.

ph_log2_diff_max_bt_min_qt_intra_slice_luma specifies the differencebetween the base 2 logarithm of the maximum size (width or height) inluma samples of a luma coding block that can be split using a binarysplit and the minimum size (width or height) in luma samples of a lumaleaf block resulting from quadtree splitting of a CTU in slices withslice_type equal to 2 (I) associated with the PH. The value ofph_log2_diff_max_bt_min_qt_intra_slice_luma shall be in the range of 0to CtbLog2SizeY-MinQtLog2SizeIntraY, inclusive. When not present, thevalue of ph_log2_diff_max_bt_min_qt_intra_slice_luma is inferred to beequal to sps_log2_diff_max_bt_min_qt_intra_slice_luma.

ph_log2_diff_max_tt_min_qt_intra_slice_luma specifies the differencebetween the base 2 logarithm of the maximum size (width or height) inluma samples of a luma coding block that can be split using a ternarysplit and the minimum size (width or height) in luma samples of a lumaleaf block resulting from quadtree splitting of a CTU in slices withslice_type equal to 2 (I) associated with the PH. The value ofph_log2_diff_max_tt_min_qt_intra_slice_luma shall be in the range of 0to CtbLog2SizeY-MinQtLog2SizeIntraY, inclusive. When not present, thevalue of ph_log2_diff_max_tt_min_qt_intra_slice_luma is inferred to beequal to sps_log2_diff_max_tt_min_qt_intra_slice_luma.

ph_log2_diff_min_qt_min_cb_intra_slice_chroma specifies the differencebetween the base 2 logarithm of the minimum size in luma samples of achroma leaf block resulting from quadtree splitting of a chroma CTU withtreeType equal to DUAL_TREE_CHROMA and the base 2 logarithm of theminimum coding block size in luma samples for chroma CUs with treeTypeequal to DUAL_TREE_CHROMA in slices with slice_type equal to 2 (I)associated with the PH. The value ofph_log2_diff_min_qt_min_cb_intra_slice_chroma shall be in the range of 0to CtbLog2SizeY-MinCbLog2SizeY, inclusive. When not present, the valueof ph_log2_diff_min_qt_min_cb_intra_slice_chroma is inferred to be equalto sps_log2_diff_min_qt_min_cb_intra_slice_chroma.

ph_max_mtt_hierarchy_depth_intra_slice_chroma specifies the maximumhierarchy depth for chroma coding units resulting from multi-type treesplitting of a chroma quadtree leaf with treeType equal toDUAL_TREE_CHROMA in slices with slice_type equal to 2 (I) associatedwith the PH. The value of ph_max_mtt_hierarchy_depth_intra_slice_chromashall be in the range of 0 to 2*(CtbLog2SizeY-MinCbLog2SizeY),inclusive. When not present, the value ofph_max_mtt_hierarchy_depth_intra_slice_chroma is inferred to be equal tosps_max_mtt_hierarchy_depth_intra_slice_chroma.

ph_log2_diff_max_bt_min_qt_intra_slice_chroma specifies the differencebetween the base 2 logarithm of the maximum size (width or height) inluma samples of a chroma coding block that can be split using a binarysplit and the minimum size (width or height) in luma samples of a chromaleaf block resulting from quadtree splitting of a chroma CTU withtreeType equal to DUAL_TREE_CHROMA in slices with slice_type equal to 2(I) associated with the PH. The value ofph_log2_diff_max_bt_min_qt_intra_slice_chroma shall be in the range of 0to CtbLog2SizeY-MinQtLog2SizeIntraC, inclusive. When not present, thevalue of ph_log2_diff_max_bt_min_qt_intra_slice_chroma is inferred to beequal to sps_log2_diff_max_bt_min_qt_intra_slice_chroma.

ph_log2_diff_max_tt_min_qt_intra_slice_chroma specifies the differencebetween the base 2 logarithm of the maximum size (width or height) inluma samples of a chroma coding block that can be split using a ternarysplit and the minimum size (width or height) in luma samples of a chromaleaf block resulting from quadtree splitting of a chroma CTU withtreeType equal to DUAL_TREE_CHROMA in slices with slice_type equal to 2(I) associated with the PH. The value ofph_log2_diff_max_tt_min_qt_intra_slice_chroma shall be in the range of 0to CtbLog2SizeY-MinQtLog2SizeIntraC, inclusive. When not present, thevalue of ph_log2_diff_max_tt_min_qt_intra_slice_chroma is inferred to beequal to sps_log2_diff_max_tt_min_qt_intra_slice_chroma.

ph_cu_qp_delta_subdiv_intra_slice specifies the maximum cbSubdiv valueof coding units in intra slice that convey cu_qp_delta_abs andcu_qp_delta_sign_flag. The value of ph_cu_qp_delta_subdiv_intra_sliceshall be in the range of 0 to 2*(CtbLog2SizeY-MinQtLog2SizeIntraY+ph_max_mtt_hierarchy_depth_intra_slice_luma),inclusive. When not present, the value ofph_cu_qp_delta_subdiv_intra_slice is inferred to be equal to 0.

ph_cu_chroma_qp_offset_subdiv_intra_slice specifies the maximum cbSubdivvalue of coding units in intra slice that conveycu_chroma_qp_offset_flag. The value ofph_cu_chroma_qp_offset_subdiv_intra_slice shall be in the range of 0 to2*(CtbLog2SizeY-MinQtLog2SizeIntraY+ph_max_mtt_hierarchy_depth_intra_slice_luma),inclusive.

When not present, the value of ph_cu_chroma_qp_offset_subdiv_intra_sliceis inferred to be equal to 0.

ph_log2_diff_min_qt_min_cb_inter_slice specifies the difference betweenthe base 2 logarithm of the minimum size in luma samples of a luma leafblock resulting from quadtree splitting of a CTU and the base 2logarithm of the minimum luma coding block size in luma samples for lumaCUs in the slices with slice_type equal to 0 (B) or 1 (P) associatedwith the PH. The value of ph_log2_diff_min_qt_min_cb_inter_slice shallbe in the range of 0 to CtbLog2SizeY-MinCbLog2SizeY, inclusive. When notpresent, the value of ph_log2_diff_min_qt_min_cb_luma is inferred to beequal to sps_log2_diff_min_qt_min_cb_inter_slice.

ph_max_mtt_hierarchy_depth_interslice specifies the maximum hierarchydepth for coding units resulting from multi-type tree splitting of aquadtree leaf in slices with slice_type equal to 0 (B) or 1 (P)associated with the PH. The value ofph_max_mtt_hierarchy_depth_inter_slice shall be in the range of 0 to2*(CtbLog2SizeY-MinCbLog2SizeY), inclusive. When not present, the valueof ph_max_mtt_hierarchy_depth_inter_slice is inferred to be equal tosps_max_mtt_hierarchy_depth_inter_slice.

ph_log2_diff_max_bt_min_qt_inter_slice specifies the difference betweenthe base 2 logarithm of the maximum size (width or height) in lumasamples of a luma coding block that can be split using a binary splitand the minimum size (width or height) in luma samples of a luma leafblock resulting from quadtree splitting of a CTU in the slices withslice_type equal to 0 (B) or 1 (P) associated with the PH. The value ofph_log2_diff_max_bt_min_qt_inter_slice shall be in the range of 0 toCtbLog2SizeY-MinQtLog2SizeInterY, inclusive. When not present, the valueof ph_log2_diff_max_bt_min_qt_inter_slice is inferred to be equal tosps_log2_diff_max_bt_min_qt_inter_slice.

ph_log2_diff_max_tt_min_qt_inter_slice specifies the difference betweenthe base 2 logarithm of the maximum size (width or height) in lumasamples of a luma coding block that can be split using a ternary splitand the minimum size (width or height) in luma samples of a luma leafblock resulting from quadtree splitting of a CTU in slices withslice_type equal to 0 (B) or 1 (P) associated with the PH. The value ofph_log2_diff_max_tt_min_qt_inter_slice shall be in the range of 0 toCtbLog2SizeY-MinQtLog2SizeInterY, inclusive. When not present, the valueof ph_log2_diff_max_tt_min_qt_inter_slice is inferred to be equal tosps_log2_diff_max_tt_minqt_inter_slice.

ph_cu_qp_delta_subdiv_inter_slice specifies the maximum cbSubdiv valueof coding units that in inter slice convey cu_qp_delta_abs andcu_qp_delta_sign_flag. The value of ph_cu_qp_delta_subdiv_inter_sliceshall be in the range of 0 to 2*(CtbLog2SizeY-MinQtLog2SizeInterY+ph_max_mtt_hierarchy_depth_inter_slice),inclusive. When not present, the value ofph_cu_qp_delta_subdiv_inter_slice is inferred to be equal to 0.

ph_cu_chroma_qp_offset_subdiv_inter_slice specifies the maximum cbSubdivvalue of coding units in inter slice that conveycu_chroma_qp_offset_flag. The value ofph_cu_chroma_qp_offset_subdiv_inter_slice shall be in the range of 0 to2*(CtbLog2SizeY-MinQtLog2SizeInterY+ph_max_mtt_hierarchy_depth_inter_slice),inclusive. When not present, the value ofph_cu_chroma_qp_offset_subdiv_inter_slice is inferred to be equal to 0.

ph_temporal_mvp_enabled_flag specifies whether temporal motion vectorpredictors can be used for inter prediction for slices associated withthe PH. If ph_temporal_mvp_enabled_flag is equal to 0, the syntaxelements of the slices associated with the PH shall be constrained suchthat no temporal motion vector predictor is used in decoding of theslices. Otherwise (ph_temporal_mvp_enabled_flag is equal to 1), temporalmotion vector predictors may be used in decoding of the slicesassociated with the PH. When not present, the value ofph_temporal_mvp_enabled_flag is inferred to be equal to 0. When noreference picture in the DPB has the same spatial resolution as thecurrent picture, the value of ph_temporal_mvp_enabled_flag shall beequal to 0.

The maximum number of subblock-based merging MW candidates,MaxNumSubblockMergeCand, is derived as follows:

if( sps_affine_enabled_flag )  MaxNumSubblockMergeCand = 5 − (88) five_minus_max_num_subblock_merge_cand  else  MaxNumSubblockMergeCand =sps_sbtmvp_enabled_flag &&  ph_temporal_mvp_enable_flag

The value of MaxNumSubblockMergeCand shall be in the range of 0 to 5,inclusive.

ph_collocated_from_10_flag equal to 1 specifies that the collocatedpicture used for temporal motion vector prediction is derived fromreference picture list 0. ph_collocated_from_10_flag equal to 0specifies that the collocated picture used for temporal motion vectorprediction is derived from reference picture list 1.

ph_collocated_ref_idx specifies the reference index of the collocatedpicture used for temporal motion vector prediction.

When ph_collocated_from_10_flag is equal to 1, ph_collocated_ref_idxrefers to an entry in reference picture list 0, and the value ofph_collocated_ref_idx shall be in the range of 0 tonum_ref_entries[0][RplsIdx[0]] −1, inclusive. Whenph_collocated_from_10_flag is equal to 0, ph_collocated_ref_idx refersto an entry in reference picture list 1, and the value ofph_collocated_ref_idx shall be in the range of 0 tonum_ref_entries[1][RplsIdx[1]] −1, inclusive. When not present, thevalue of ph_collocated_ref_idx is inferred to be equal to 0.

mvd_l1_zero_flag equal to 1 indicates that the mvd_coding(x0, y0, 1)syntax structure is not parsed and MvdL1[x0][y0][compIdx] andMvdCpL1[x0][y0][cpIdx][compIdx] are set equal to 0 for compIdx=0.1 andcpIdx=0.2. mvd_l1_zero_flag equal to 0 indicates that the mvd_coding(x0,y0, 1) syntax structure is parsed.

ph_fpel_mmvd_enabled_flag equal to 1 specifies that merge mode withmotion vector difference uses integer sample precision in the slicesassociated with the PH. ph_fpel_mmvd_enabled_flag equal to 0 specifiesthat merge mode with motion vector difference can use fractional sampleprecision in the slices associated with the PH. When not present, thevalue of ph_fpel_mmvd_enabled_flag is inferred to be 0.

ph_disable_bdof_flag equal to 1 specifies that bi-directional opticalflow inter prediction based inter bi-prediction is disabled in theslices associated with the PH. ph_disable_bdof_flag equal to 0 specifiesthat bi-directional optical flow inter prediction based interbi-prediction may or may not be enabled in the slices associated withthe PH. When ph_disable_bdof_flag is not present, the following applies:

-   -   If sps_bdof_enabled_flag is equal to 1, the value of        ph_disable_bdof_flag is inferred to be equal to 0.    -   Otherwise (sps_bdof_enabled_flag is equal to 0), the value of        ph_disable_bdof_flag is inferred to be equal to 1.

ph_disable_dmvr_flag equal to 1 specifies that decoder motion vectorrefinement based inter bi-prediction is disabled in the slicesassociated with the PH. ph_disable_dmvr_flag equal to 0 specifies thatdecoder motion vector refinement based inter bi-prediction may or maynot be enabled in the slices associated with the PH.

When ph_disable_dmvr_flag is not present, the following applies:

-   -   If sps_dmvr_enabled_flag is equal to 1, the value of        ph_disable_dmvr_flag is inferred to be equal to 0.    -   Otherwise (sps_dmvr_enabled_flag is equal to 0), the value of        ph_disable_dmvr_flag is inferred to be equal to 1.

ph_disable_prof_flag equal to 1 specifies that prediction refinementwith optical flow is disabled in the slices associated with the PH.ph_disable_prof_flag equal to 0 specifies that prediction refinementwith optical flow may or may not be enabled in the slices associatedwith the PH.

When ph_disable_prof_flag is not present, the following applies:

-   -   If sps_affine_prof_enabled_flag is equal to 1, the value of        ph_disable_prof_flag is inferred to be equal to 0.    -   Otherwise (sps_affine_prof_enabled_flag is equal to 0), the        value of ph_disable_prof_flag is inferred to be equal to 1.

ph_qp_delta specifies the initial value of Qp_(Y) to be used for thecoding blocks in the picture until modified by the value of CuQpDeltaValin the coding unit layer.

When qp_delta_info_in_ph_flag is equal to 1, the initial value of theQp_(Y) quantization parameter for all slices of the picture,SliceQp_(Y), is derived as follows:

SliceQp_(Y)=26+init_qp_minus26+ph_qp_delta   (89)

The value of SliceQp_(Y) shall be in the range of −QpBdOffset to +63,inclusive.

ph_joint_cbcr_sign_flag specifies whether, in transform units withtu_joint_cbcr_residual_flag[x0][y0] equal to 1, the collocated residualsamples of both chroma components have inverted signs. Whentu_joint_cbcr_residual_flag[x0][y0] equal to 1 for a transform unit,ph_joint_cbcr_sign_flag equal to 0 specifies that the sign of eachresidual sample of the Cr (or Cb) component is identical to the sign ofthe collocated Cb (or Cr) residual sample and ph_joint_cbcr_sign_flagequal to 1 specifies that the sign of each residual sample of the Cr (orCb) component is given by the inverted sign of the collocated Cb (or Cr)residual sample

ph_sao_luma_enabled_flag equal to 1 specifies that SAO is enabled forthe luma component in all slices associated with the PH;ph_sao_luma_enabled_flag equal to 0 specifies that SAO for the lumacomponent may be disabled for one, or more, or all slices associatedwith the PH. When ph_sao_luma_enabled_flag is not present, it isinferred to be equal to 0.

ph_sao_chroma_enabled_flag equal to 1 specifies that SAO is enabled forthe chroma component in all slices associated with the PH;ph_sao_chroma_enabled_flag equal to 0 specifies that SAO for chromacomponent may be disabled for one, or more, or all slices associatedwith the PH. When ph_sao_chroma_enabled_flag is not present, it isinferred to be equal to 0.

ph_dep_quant_enabled_flag equal to 0 specifies that dependentquantization is disabled for the current picture.ph_dep_quant_enabled_flag equal to 1 specifies that dependentquantization is enabled for the current picture. Whenph_dep_quant_enabled_flag is not present, it is inferred to be equal to0.

pic_sign_data_hiding_enabled_flag equal to 0 specifies that sign bithiding is disabled for the current picture.pic_sign_data_hiding_enabled_flag equal to 1 specifies that sign bithiding is enabled for the current picture. Whenpic_sign_data_hiding_enabled_flag is not present, it is inferred to beequal to 0.

ph_deblocking_filter_override_flag equal to 1 specifies that deblockingparameters are present in the PH. ph_deblocking_filter_override_flagequal to 0 specifies that deblocking parameters are not present in thePH. When not present, the value of ph_deblocking_filter_override_flag isinferred to be equal to 0.

ph_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of the deblocking filter is not applied for the slicesassociated with the PH. ph_deblocking_filter_disabled_flag equal to 0specifies that the operation of the deblocking filter is applied for theslices associated with the PH. When ph_deblocking_filter_disabled_flagis not present, it is inferred to be equal topps_deblocking_filter_disabled_flag.

ph_beta_offset_div2 and ph_tc_offset_div2 specify the deblockingparameter offsets for β and tC (divided by 2) that are applied to theluma component for the slices associated with the PH. The values ofph_beta_offset_div2 and ph_tc_offset_div2 shall both be in the range of−12 to 12, inclusive. When not present, the values ofph_beta_offset_div2 and ph_tc_offset_div2 are inferred to be equal topps_beta_offset_div2 and pps_tc_offset_div2, respectively.

ph_cb_beta_offset_div2 and ph_cb_tc_offset_div2 specify the deblockingparameter offsets for β and tC (divided by 2) that are applied to the Cbcomponent for the slices associated with the PH. The values ofph_cb_beta_offset_div2 and ph_cb_tc_offset_div2 shall both be in therange of −12 to 12, inclusive. When not present, the values ofph_cb_betaoffset_div2 and ph_cb_tc_offset_div2 are inferred to be equalto pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2, respectively.

ph_cr_beta_offset_div2 and ph_cr_tc_offset_div2 specify the deblockingparameter offsets for β and tC (divided by 2) that are applied to the Crcomponent for the slices associated with the PH. The values ofph_cr_beta_offset_div2 and ph_cr_tc_offset_div2 shall both be in therange of −12 to 12, inclusive. When not present, the values ofph_cr_betaoffset_div2 and ph_cr_tc_offset_div2 are inferred to be equalto pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2, respectively.

ph_extension_length specifies the length of the PH extension data inbytes, not including the bits used for signalling ph_extension_lengthitself. The value of ph_extension_length shall be in the range of 0 to256, inclusive. When not present, the value of ph_extension_length isinferred to be equal to 0.

ph_extensiondatabyte may have any value. Decoders conforming to thisversion of this Specification shall ignore the value ofph_extension_data_byte. Its value does not affect decoder conformance toprofiles specified in this version of specification.

3.4. SH Syntax and Semantics

In the latest VVC draft text, the SH syntax and semantics are asfollows:

Descriptor slice_header( ) {  picture _(—) header _(—) in _(—) slice_(—) header _(—) flag u(1)  if( picture_header_in_slice_header_flag )  picture_header_structure( )  if( subpic_info_present_flag )   slice_(—) subpic _(—) id u(v)  if( ( rect_slice_flag && NumSlicesInSubpic[CurrSubpicIdx ] > 1 ) | |    ( !rect_slice_flag && NumTilesInPic > 1 ) )  slice_address u(v)  for( i = 0; i < NumExtraShBits; i++ )   sh _(—)extra _(—) bit[ i ] u(1)  if( !rect_slice_flag && NumTilesInPic > 1 )  num _(—) tiles _(—) in _(—) slice _(—) minus1 ue(v)  if(ph_inter_slice_allowed_flag )   slice _(—) type ue(v)  if(sps_alf_enabled_flag && !alf_info_in_ph_flag ) {   slice _(—) alf _(—)enabled _(—) flag u(1)   if( slice_alf_enabled_flag ) {    slice _(—)num _(—) alf _(—) aps _(—) ids _(—) luma u(3)    for( i = 0; i <slice_num_alf_aps_ids_luma; i++ )     slice _(—) alf _(—) aps _(—) id_(—) luma[ i ] u(3)    if( ChromaArrayType != 0 )     slice _(—) alf_(—) chroma _(—) idc u(2)    if( slice_alf_chroma_idc )     slice _(—)alf _(—) aps _(—) id _(—) chroma u(3)    if( sps_ccalf_enabled_flag ) {    slice _(—) cc _(—) alf _(—) cb _(—) enabled _(—) flag u(1)     if(slice_cc_alf_cb_enabled_flag )      slice _(—) cc _(—) alf _(—) cb _(—)aps _(—) id u(3)     slice _(—) cc _(—) alf _(—) cr _(—) enabled _(—)flag u(1)     if( slice_cc_alf_cr_enabled_flag )      slice _(—) cc _(—)alf _(—) cr _(—) aps _(—) id u(3)    }   }  }  if(separate_colour_plane_flag = = 1 )   colour _(—) plane _(—) id u(2)  if(!rpl_info_in_ph_flag && ( ( nal_unit_type != IDR_W_RADL && nal_unit_type!=    IDR_N_LP ) | | sps_idr_rpl_present_flag ) )   ref_pic_lists( ) if( ( rpl_info_in_ph_flag | | ( ( nal_unit_type != IDR_W_RADL &&nal_unit_type !=    IDR_N_LP ) | | sps_idr_rpl_present_flag ) ) &&    (slice_type != I && num_ref_entries[ 0 ][ RplsIdx[ 0 ] ] > 1 ) | |    (slice_type = = B && num_ref_entries[ 1 ][ RplsIdx[ 1 ] ] > 1 ) ) {   num_(—) ref _(—) idx _(—) active _(—) override _(—) flag u(1)   if(num_ref_idx_active_override_flag )    for( i = 0; i < ( slice_type = = B? 2: 1 ); i++ )     if( num_ref_entries[ i ][ RplsIdx[ i ] ] > 1 )     num _(—) ref _(—) idx _(—) active _(—) minus1[ i ] ue(v)  }  if(slice_type != I ) {   if( cabac_init_present_flag )    cabac _(—) init_(—) flag u(1)   if( ph_temporal_mvp_enabled_flag &&!rpl_info_in_ph_flag ) {    if( slice_type = = B )     slice _(—)collocated _(—) from _(—) l0 _(—) flag u(1)    if( (slice_collocated_from_l0_flag && NumRefIdxActive[ 0 ] > 1 ) | |      ( !slice_collocated_from_l0_flag && NumRefIdxActive[ 1 ] > 1 ) )     slice_(—) collocated _(—) ref _(—) idx ue(v)   }   if( !wp_info_in_ph_flag &&(( pps_weighted_pred_flag && slice_type = = P ) | |     (pps_weighted_bipred_flag && slice_type = = B ) ) )    pred_weight_table()  }  if( !qp_delta_info_in_ph_flag )   slice _(—) qp _(—) delta se(v) if( pps_slice_chroma_qp_offsets_present_flag ) {   slice _(—) cb _(—)qp _(—) offset se(v)   slice _(—) cr _(—) qp _(—) offset se(v)   if(sps_joint_cbcr_enabled_flag )    slice _(—) joint _(—) cbcr _(—) qp _(—)offset se(v)  }  if( pps_cu_chroma_qp_offset_list_enabled_flag )   cu_(—) chroma _(—) qp _(—) offset _(—) enabled _(—) flag u(1)  if(sps_sao_enabled_flag && !sao_info_in_ph_flag ) {   slice _(—) sao _(—)luma _(—) flag u(1)   if( ChromaArrayType != 0 )    slice _(—) sao _(—)chroma _(—) flag u(1)  }  if( deblocking_filter_override_enabled_flag &&!dbf_info_in_ph_flag )   slice _(—) deblocking _(—) filter _(—) override_(—) flag u(1)  if( slice_deblocking_filter_override_flag ) {   slice_(—) deblocking _(—) filter _(—) disabled _(—) flag u(1)   if(!slice_deblocking_filter_disabled_flag ) {    slice _(—) beta _(—)offset _(—) div2 se(v)    slice _(—) tc _(—) offset _(—) div2 se(v)   slice _(—) cb _(—) beta _(—) offset _(—) div2 se(v)    slice _(—) cb_(—) tc _(—) offset _(—) div2 se(v)    slice _(—) cr _(—) beta _(—)offset _(—) div2 se(v)    slice _(—) cr _(—) tc _(—) offset _(—) div2se(v)   }  }  slice _(—) ts _(—) residual _(—) coding _(—) disabled _(—)flag u(1)  if( ph_lmcs_enabled_flag )   slice _(—) lmcs _(—) enabled_(—) flag u(1)  if( ph_scaling_list_enabled_flag )   slice _(—) scaling_(—) list _(—) present _(—) flag u(1)  if( NumEntryPoints > 0 ) {  offset _(—) len _(—) minus1 ue(v)   for( i = 0; i < NumEntryPoints;i++ )    entry _(—) point _(—) offset _(—) minus1[ i ] u(v)  }  if(slice_header_extension_present_flag ) {   slice _(—) header _(—)extension _(—) length ue(v)   for( i = 0; i <slice_header_extension_length; i++)    slice _(—) header _(—) extension_(—) data _(—) byte[ i ] u(8)  }  byte_alignment( ) }

The variable CuQpDeltaVal, specifying the difference between a lumaquantization parameter for the coding unit containing cu_qp_delta_absand its prediction, is set equal to 0. The variables CuQpOffset_(Cb),CuQpOffset_(Cr), and CuQpOffset_(CbCr), specifying values to be usedwhen determining the respective values of the Qp′_(Cb), Qp′_(Cr), andQp′_(CbCr) quantization parameters for the coding unit containingcu_chroma_qp_offset_flag, are all set equal to 0.

picture_header_in_slice_header_flag equal to 1 specifies that the PHsyntax structure is present in the slice header.picture_header_in_slice_header_flag equal to 0 specifies that the PHsyntax structure is not present in the slice header. It is a requirementof bitstream conformance that the value ofpicture_header_in_slice_header_flag shall be the same in all codedslices in a CLVS.

When picture_header_in_slice_header_flag is equal to 1 for a codedslice, it is a requirement of bitstream conformance that no VCL NAL unitwith nal_unit_type equal to PH_NUT shall be present in the CLVS.

When picture_header_in_slice_header_flag is equal to 0, all coded slicesin the current picture shall have picture_header_in_slice_header_flag isequal to 0, and the current PU shall have a PH NAL unit.

slice_subpic_id specifies the subpicture ID of the subpicture thatcontains the slice. If slice_subpic_id is present, the value of thevariable CurrSubpicIdx is derived to be such thatSubpicIdVal[CurrSubpicIdx] is equal to slice_subpic_id. Otherwise(slice_subpic_id is not present), CurrSubpicIdx is derived to be equalto 0. The length of slice_subpic_id is sps_subpic_id_len_minus1+1 bits.

slice_address specifies the slice address of the slice. When notpresent, the value of slice_address is inferred to be equal to 0. Whenrect_slice_flag is equal to 1 and NumSlicesInSubpic[CurrSubpicIdx] isequal to 1, the value of slice_address is inferred to be equal to 0.

If rect_slice_flag is equal to 0, the following applies:

-   -   The slice address is the raster scan tile index.    -   The length of slice_address is Ceil(Log2 (NumTilesInPic)) bits.    -   The value of slice_address shall be in the range of 0 to        NumTilesInPic −1, inclusive.

Otherwise (rect_slice_flag is equal to 1), the following applies:

-   -   The slice address is the subpicture-level slice index of the        slice.    -   The length of slice_address is        Ceil(Log2(NumSlicesInSubpic[CurrSubpicIdx])) bits.    -   The value of slice_address shall be in the range of 0 to        NumSlicesInSubpic[CurrSubpicIdx]−1, inclusive.

It is a requirement of bitstream conformance that the followingconstraints apply:

-   -   If rect_slice_flag is equal to 0 or subpic_info_present_flag is        equal to 0, the value of slice_address shall not be equal to the        value of slice_address of any other coded slice NAL unit of the        same coded picture.    -   Otherwise, the pair of slice_subpic_id and slice_address values        shall not be equal to the pair of slice_subpic_id and        slice_address values of any other coded slice NAL unit of the        same coded picture.    -   The shapes of the slices of a picture shall be such that each        CTU, when decoded, shall have its entire left boundary and        entire top boundary consisting of a picture boundary or        consisting of boundaries of previously decoded CTU(s).

sh_extra_bit[i] may be equal to 1 or 0. Decoders conforming to thisversion of this Specification shall ignore the value of sh_extra_bit[i].Its value does not affect decoder conformance to profiles specified inthis version of specification.

num_tiles_in_slice_minus1 plus 1, when present, specifies the number oftiles in the slice. The value of num_tiles_in_slice_minus1 shall be inthe range of 0 to NumTilesInPic −1, inclusive.

The variable NumCtusInCurrSlice, which specifies the number of CTUs inthe current slice, and the list CtbAddrInCurrSlice[i], for i rangingfrom 0 to NumCtusInCurrSlice −1, inclusive, specifying the pictureraster scan address of the i-th CTB within the slice, are derived asfollows:

if( rect_slice_flag ) {  picLevelSliceIdx = slice_address  for( j = 0; j< CurrSubpicIdx; j++ )   picLevelSliceIdx += NumSlicesInSubpic[ j ] NumCtusInCurrSlice = NumCtusInSlice[ picLevelSliceIdx ]  for( i = 0; i< NumCtusInCurrSlice; i++ )   CtbAddrInCurrSlice[ i ] = CtbAddrInSlice[(117)   picLevelSliceIdx ][ i ] } else {  NumCtusInCurrSlice = 0  for(tileIdx = slice_address; tileIdx <=  slice_address +num_tiles_in_slice_minus1; tileIdx++ ) {   tileX = tileIdx %NumTileColumns   tileY = tileIdx / NumTileColumns   for( ctbY =tileRowBd[ tileY ]; ctbY < tileRowBd[ tileY + 1 ];   ctbY++ ) {    for(ctbX = tileColBd[ tileX ]; ctbX < tileColBd[ tileX + 1 ];    ctbX++ ) {    CtbAddrInCurrSlice[ NumCtusInCurrSlice ] = ctbY *    PicWidthInCtb + ctbX     NumCtusInCurrSlice++    }   }  } }

The variables SubpicLeftBoundaryPos, SubpicTopBoundaryPos,SubpicRightBoundaryPos, and SubpicBotBoundaryPos are derived as follows:

if( subpic_treated_as_pic_flag[ CurrSubpicIdx ] ) { SubpicLeftBoundaryPos = subpic_ctu_top_left_x[  CurrSubpicIdx ] *CtbSizeY  SubpicRightBoundaryPos = Min(  pic_width_max_in_luma_samples −1,   ( subpic_ctu_top_left_x[ CurrSubpicIdx ] +   subpic_width_minus1[CurrSubpicIdx ] + 1 ) * CtbSizeY − 1 )  SubpicTopBoundaryPos =subpic_ctu_top_left_y[ (118)  CurrSubpicIdx ] *CtbSizeY SubpicBotBoundaryPos = Min(  pic_height_max_in_luma_samples − 1,   (subpic_ctu_top_left_y[ CurrSubpicIdx ] +   subpic_height_minus1[CurrSubpicIdx ] + 1 ) * CtbSizeY − 1 ) }

slice_type specifies the coding type of the slice according to Table 9.

TABLE 9 Name association to slice_type slice_type Name of slice_type 0 B(B slice) 1 P (P slice) 2 I (I slice)

When not present, the value of slice_type is inferred to be equal to 2.

When ph_intra_slice_allowed_flag is equal to 0, the value of slice_typeshall be equal to 0 or 1. When nal_unit_type is in the range ofIDRW_RADL to CRA_NUT, inclusive, andvps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id]] is equal to 1,slice_type shall be equal to 2.

The variables MinQtLog2SizeY, MinQtLog2SizeC, MinQtSizeY, MinQtSizeC,MaxBtSizeY, MaxBtSizeC, MinBtSizeY, MaxTtSizeY, MaxTtSizeC, MinTtSizeY,MaxMttDepthY and MaxMttDepthC are derived as follows:

-   -   If slice_type equal to 2 (I), the following applies:

MinQtLog2SizeY=MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_intra_slice_luma  (119)

MinQtLog2SizeC=MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_intra_slice_chroma  (120)

MaxBtSizeY=1«(MinQtLog2SizeY+ph_log2_diff_max_bt_min_qt_intra_slice_luma)  (121)

MaxBtSizeC=1«(MinQtLog2SizeC+ph_log2_diff_max_bt_min_qt_intra_slice_chroma)  (122)

MaxTtSizeY=1«(MinQtLog2SizeY+ph_log2_diff_max_tt_min_qt_intra_slice_luma)  (123)

MaxTtSizeC=1«(MinQtLog2SizeC+ph_log2_diff_max_tt_minqt_intra_slice_chroma)  (124)

MaxMttDepthY=ph_max_mtt_hierarchy_depth_intra_slice_luma   (125)

MaxMttDepthC=phmax_mtt_hierarchy_depth_intra_slice_chroma   (126)

CuQpDeltaSubdiv=ph_cu_qp_delta_subdiv_intra_slice   (127)

CuChromaQpOffsetSubdiv=ph_cu_chroma_qp_offset_subdiv_intra_slice   (128)

Otherwise (slice_type equal to 0 (B) or 1 (P)), the following applies:

MinQtLog2SizeY=MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_inter_slice  (129)

MinQtLog2SizeC=MinCbLog2SizeY+ph_log2_diff_min_qt_min_cb_inter_slice  (130)

MaxBtSizeY=1«(MinQtLog2SizeY+ph_log2_diff_max_bt_min_qt_inter_slice)  (131)

MaxBtSizeC=1«(MinQtLog2SizeC+ph_log2_diff_max_bt_min_qt_inter_slice)  (132)

MaxTtSizeY=1«(MinQtLog2SizeY+ph_log2_diff_max_tt_min_qt_inter_slice)  (133)

MaxTtSizeC=1«(MinQtLog2SizeC+ph_log2_diff_max_tt_minqt_inter_slice)  (134)

MaxMttDepthY=ph_max_mtt_hierarchy_depth_inter_slice   (135)

MaxMttDepthC=ph_max_mtt_hierarchy_depth_inter_slice   (136)

CuQpDeltaSubdiv=ph_cu_qp_delta_subdiv_inter_slice   (137)

CuChromaQpOffsetSubdiv=ph_cu_chroma_qp_offset_subdiv_inter_slice   (138)

The following applies:

MinQtSizeY=1«MinQtLog2SizeY   (139)

MinQtSizeC=1«MinQtLog2SizeC   (140)

MinBtSizeY=1«MinCbLog2SizeY   (141)

MinTtSizeY=1«MinCbLog2SizeY   (142)

slice_alf_enabled_flag equal to 1 specifies that adaptive loop filter isenabled and may be applied to Y, Cb, or Cr colour component in a slice.slice_alf_enabled_flag equal to 0 specifies that adaptive loop filter isdisabled for all colour components in a slice. When not present, thevalue of slice_alf_enabled_flag is inferred to be equal toph_alf_enabled_flag.

slice_num_alf_aps_ids_luma specifies the number of ALF APSs that theslice refers to. When slice_alf_enabled_flag is equal to 1 andslice_num_alf_aps_ids_luma is not present, the value ofslice_num_alf_aps_ids_luma is inferred to be equal to the value ofph_num_alf_aps_ids_luma.

slice_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id ofthe i-th ALF APS that the luma component of the slice refers to. TheTemporalId of the APS NAL unit having aps_params_type equal to ALF_APSand adaptation_parameter_set_id equal to slice_alf_aps_id_luma[i] shallbe less than or equal to the TemporalId of the coded slice NAL unit.When slice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_luma[i]is not present, the value of slice_alf_aps_id_luma[i] is inferred to beequal to the value of ph_alf_aps_id_luma[i]. The value ofalf_luma_filter_signal_flag of the APS NAL unit having aps_params_typeequal to ALF_APS and adaptation_parameter_set_id equal toslice_alf_aps_id_luma[i] shall be equal to 1.

slice_alf_chroma_idc equal to 0 specifies that the adaptive loop filteris not applied to Cb and Cr colour components. slice_alf_chroma_idcequal to 1 indicates that the adaptive loop filter is applied to the Cbcolour component. slice_alf_chroma_idc equal to 2 indicates that theadaptive loop filter is applied to the Cr colour component.slice_alf_chroma _idc equal to 3 indicates that the adaptive loop filteris applied to Cb and Cr colour components. When slice_alf_chroma _idc isnot present, it is inferred to be equal to ph_alf_chroma_idc.

slice_alf_aps_id_chroma specifies the adaptation_parameter_set_id of theALF APS that the chroma component of the slice refers to. The TemporalIdof the APS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_alf_aps_id_chroma shall beless than or equal to the TemporalId of the coded slice NAL unit. Whenslice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_chroma is notpresent, the value of slice_alf_aps_id_chroma is inferred to be equal tothe value of ph_alf_aps_id_chroma.

The value of alf_chroma_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto slice_alf_aps_id_chroma shall be equal to 1.

slice_cc_alf_cb_enabled_flag equal to 0 specifies that thecross-component filter is not applied to the Cb colour component.slice_cc_alf_cb_enabled_flag equal to 1 indicates that thecross-component filter is enabled and may be applied to the Cb colourcomponent. When slice_cc_alf_cb_enabled_flag is not present, it isinferred to be equal to ph_cc_alf_cb_enabled_flag.

slice_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id thatthe Cb colour component of the slice refers to. The TemporalId of theAPS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_cc_alf_cb_aps_id shall beless than or equal to the TemporalId of the coded slice NAL unit. Whenslice_cc_alf_cb_enabled_flag is equal to 1 and slice_cc_alf_cb_aps_id isnot present, the value of slice_cc_alf_cb_aps_id is inferred to be equalto the value of ph_cc_alf_cb_aps_id.

The value of alf_cc_cb_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto slice_cc_alf_cb_aps_id shall be equal to 1.

slice_cc_alf_cr_enabled_flag equal to 0 specifies that thecross-component filter is not applied to the Cr colour component.slice_cc_alf_cb_enabled_flag equal to 1 indicates that thecross-component adaptive loop filter is enabled and may be applied tothe Cr colour component. When slice_cc_alf_cr_enabled_flag is notpresent, it is inferred to be equal to ph_cc_alf_cr_enabled_flag.

slice_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id thatthe Cr colour component of the slice refers to. The TemporalId of theAPS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_cc_alf_cr_aps_id shall beless than or equal to the TemporalId of the coded slice NAL unit. Whenslice_cc_alf_cr_enabled_flag is equal to 1 and slice_cc_alf_cr_aps_id isnot present, the value of slice_cc_alf_cr_aps_id is inferred to be equalto the value of ph_cc_alf_cr_aps_id.

The value of alf_cc_cr_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto slice_cc_alf_cr_aps_id shall be equal to 1.

colour_plane_id identifies the colour plane associated with the currentslice when separate_colour_plane_flag is equal to 1. The value ofcolour_plane_id shall be in the range of 0 to 2, inclusive.colour_plane_id values 0, 1 and 2 correspond to the Y, Cb and Cr planes,respectively. The value 3 of colour_plane_id is reserved for future useby ITU-T|ISO/IEC.

-   -   NOTE 1—There is no dependency between the decoding processes of        different colour planes of one picture.

num_ref_idx_active_override_flag equal to 1 specifies that the syntaxelement num_ref_idx_active_minus1[0] is present for P and B slices andthe syntax element num_ref_idx_active_minus1[1] is present for B slices.num_ref_idx_active_override_flag equal to 0 specifies that the syntaxelements num_ref_idx_active_minus1[0] and num_ref_idx_active_minus1[1]are not present. When not present, the value ofnum_ref_idx_active_override_flag is inferred to be equal to 1.

num_ref_idx_active_minus1[i] is used for the derivation of the variableNumRefIdxActive[i] as specified by Equation 143. The value ofnum_ref_idx_active_minus1[i] shall be in the range of 0 to 14,inclusive. For i equal to 0 or 1, when the current slice is a B slice,num_ref_idx_active_override_flag is equal to 1, andnum_ref_idx_active_minus1[i] is not present,num_ref_idx_active_minus1[i] is inferred to be equal to 0.

When the current slice is a P slice, num_ref_idx_active_override_flag isequal to 1, and num_ref_idx_active_minus1[0] is not present,num_ref_idx_active_minus1[0] is inferred to be equal to 0.

The variable NumRefIdxActive[i] is derived as follows:

for( i = 0; i < 2; i++ ) {  if( slice_type = = B | | ( slice_type = = P&& i = = 0 ) ) {   if( num_ref_idx_active_override_flag )   NumRefIdxActive[ i ] = (143)    num_ref_idx_active_minus1[ i ] + 1  else {    if( num_ref_entries[ i ][ RplsIdx[ i ] ] >=   num_ref_idx_default_active_minus1[ i ] + 1 )     NumRefIdxActive[ i ]=     num_ref_idx_default_active_minus1[ i ] + 1    else    NumRefIdxActive[ i ] = num_ref_entries[ i ][ RplsIdx[ i ] ]   }  }else /* slice_type = = I | | ( slice_type = = P && i = = 1 ) */  NumRefIdxActive[ i ] = 0 }

The value of NumRefIdxActive[i] −1 specifies the maximum reference indexfor reference picture list i that may be used to decode the slice. Whenthe value of NumRefIdxActive[i] is equal to 0, no reference index forreference picture list i may be used to decode the slice.

When the current slice is a P slice, the value of NumRefIdxActive[0]shall be greater than 0.

When the current slice is a B slice, both NumRefIdxActive[0] andNumRefIdxActive[1] shall be greater than 0.

cabac_init_flag specifies the method for determining the initializationtable used in the initialization process for context variables. Whencabac_init_flag is not present, it is inferred to be equal to 0.

slice_collocated_from_10_flag equal to 1 specifies that the collocatedpicture used for temporal motion vector prediction is derived fromreference picture list 0. slice_collocated_from_10_flag equal to 0specifies that the collocated picture used for temporal motion vectorprediction is derived from reference picture list 1.

When slice_type is equal to B or P, ph_temporal_mvp_enabled_flag isequal to 1, and slice_collocated_from_10_flag is not present, thefollowing applies:

-   -   If rpljnfo_in_phflag is equal to 1,        slice_collocated_from_10_flag is inferred to be equal to        ph_collocated_from_10_flag.    -   Otherwise (rpl_info_in_ph_flag is equal to 0 and slice_type is        equal to P), the value of slice_collocated_from_10_flag is        inferred to be equal to 1.

slice_collocated_ref_idx specifies the reference index of the collocatedpicture used for temporal motion vector prediction.

When slice_type is equal to P or when slice_type is equal to B andslice_collocated_from_10_flag is equal to 1, slice_collocated_ref_idxrefers to an entry in reference picture list 0, and the value ofslice_collocated_ref_idx shall be in the range of 0 toNumRefIdxActive[0] −1, inclusive.

When slice_type is equal to B and slice_collocated_from_10_flag is equalto 0, slice_collocated_ref_idx refers to an entry in reference picturelist 1, and the value of slice_collocated_ref_idx shall be in the rangeof 0 to NumRefIdxActive[1] −1, inclusive.

When slice_collocated_ref_idx is not present, the following applies:

-   -   If rpl_info_in_ph_flag is equal to 1, the value of        slice_collocated_ref_idx is inferred to be equal to        ph_collocated_ref_idx.    -   Otherwise (rpl_info_in_ph_flag is equal to 0), the value of        slice_collocated_ref_idx is inferred to be equal to 0.

It is a requirement of bitstream conformance that the picture referredto by slice_collocated_ref_idx shall be the same for all slices of acoded picture.

It is a requirement of bitstream conformance that the values ofpic_width_in_luma_samples and pic_height_in_luma_samples of thereference picture referred to by slice_collocated_ref_idx shall be equalto the values of pic_width_in_luma_samples andpic_height_in_luma_samples, respectively, of the current picture, andRprConstraintsActive[slice_collocated_from_10_flag? 0 :1][slice_collocated_ref_idx] shall be equal to 0.

slice_qp_delta specifies the initial value of Qp_(Y) to be used for thecoding blocks in the slice until modified by the value of CuQpDeltaValin the coding unit layer.

When qp_delta_info_in_ph_flag is equal to 0, the initial value of theQp_(Y) quantization parameter for the slice, SliceQp_(Y), is derived asfollows:

SliceQp_(Y)=26+init_qp_minus26+slice_qp_delta   (144)

The value of SliceQp_(Y) shall be in the range of −QpBdOffset to +63,inclusive.

When either of the following conditions is true:

-   -   The value of wp_info_in_ph_flag is equal to 1,        pps_weighted_pred_flag is equal to 1, and slice_type is equal to        P.    -   The value of wp_info_in_ph_flag is equal to 1,        pps_weighted_bipred_flag is equal to 1, and slice_type is equal        to B.

the following applies:

-   -   The value of NumRefIdxActive[0] shall be less than or equal to        the value of NumWeightsL0.    -   For each reference picture index RefPicList[0][i] for i in the        range of 0 to NumRefIdxActive[0] −1, inclusive, the luma weight,        Cb weight, and Cr weight that apply to the reference picture        index are LumaWeightL0[i], ChromaWeightL0[0][i], and        ChromaWeightL0[1][i], respectively.

When wp_info_in_ph_flag is equal to 1, pps_weighted_bipred_flag is equalto 1, and slice_type is equal to B, the following applies:

-   -   The value of NumRefIdxActive[1] shall be less than or equal to        the value of NumWeightsL1.    -   For each reference picture index RefPicList[1][i] for i in the        range of 0 to NumRefIdxActive[1] −1, inclusive, the luma weight,        Cb weight, and Cr weight that apply to the reference picture        index are LumaWeightL1[i], ChromaWeightL1[0][i], and        ChromaWeightL1[1][i], respectively.

slice_cb_qp_offset specifies a difference to be added to the value ofpps_cb_qp_offset when determining the value of the Qp′_(Cb) quantizationparameter. The value of slice_cb_qp_offset shall be in the range of −12to +12, inclusive.

When slice_cb_qp_offset is not present, it is inferred to be equal to 0.The value of pps_cb_qp_offset+slice_cb_qp_offset shall be in the rangeof −12 to +12, inclusive.

slice_cr_qp_offset specifies a difference to be added to the value ofpps_cr_qp_offset when determining the value of the Qp′_(Cr),quantization parameter. The value of slice_cr_qp_offset shall be in therange of −12 to +12, inclusive. When slice_cr_qp_offset is not present,it is inferred to be equal to 0. The value ofpps_cr_qp_offset+slice_cr_qp_offset shall be in the range of −12 to +12,inclusive.

slice joint_cbcr_qp_offset specifies a difference to be added to thevalue of pps_joint_cbcr_qp_offset_value when determining the value ofthe Qp′_(CbCr). The value of slice joint_cbcr_qp_offset shall be in therange of −12 to +12, inclusive. When slice joint_cbcr_qp_offset is notpresent, it is inferred to be equal to 0. The value ofpps_joint_cbcr_qp_offset_value+slice joint_cbcr_qp_offset shall be inthe range of −12 to +12, inclusive.

cu_chroma_qp_offset_enabled_flag equal to 1 specifies that thecu_chroma_qp_offset_flag may be present in the transform unit andpalette coding syntax. cu_chroma_qp_offset_enabled_flag equal to 0specifies that the cu_chroma_qp_offset_flag is not present in thetransform unit or palette coding syntax. When not present, the value ofcu_chroma_qp_offset_enabled_flag is inferred to be equal to 0.

slice_sao_luma_flag equal to 1 specifies that SAO is enabled for theluma component in the current slice; slice_sao_lumaflag equal to 0specifies that SAO is disabled for the luma component in the currentslice. When slice_sao_lumaflag is not present, it is inferred to beequal to ph_sao_lumaenabled_flag.

slice_sao_chroma_flag equal to 1 specifies that SAO is enabled for thechroma component in the current slice; slice_sao_chromaflag equal to 0specifies that SAO is disabled for the chroma component in the currentslice. When slice_sao_chromaflag is not present, it is inferred to beequal to ph_sao_chromaenabled_flag.

slice_deblocking_filter_override_flag equal to 1 specifies thatdeblocking parameters are present in the slice header.slice_deblocking_filter_override_flag equal to 0 specifies thatdeblocking parameters are not present in the slice header. When notpresent, the value of slice_deblocking_filter_override_flag is inferredto be equal to ph_deblocking_filter_override_flag.

slice_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of the deblocking filter is not applied for the current slice.slice_deblocking_filter_disabled_flag equal to 0 specifies that theoperation of the deblocking filter is applied for the current slice.When slice_deblocking_filter_disabled_flag is not present, it isinferred to be equal to ph_deblocking_filter_disabled_flag.

slice_beta_offset_div2 and slice_tc_offset_div2 specify the deblockingparameter offsets for β and tC (divided by 2) that are applied to theluma component for the current slice. The values of slicebetaoffset_div2and slice_tc_offset_div2 shall both be in the range of −12 to 12,inclusive. When not present, the values of slicebetaoffset_div2 andslice_tc_offset_div2 are inferred to be equal to ph_beta_offset_div2 andph_tc_offset_div2, respectively.

slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 specify thedeblocking parameter offsets for β and tC (divided by 2) that areapplied to the Cb component for the current slice. The values ofslice_cb_betaoffset_div2 and slice_cb_tc_offset_div2 shall both be inthe range of −12 to 12, inclusive. When not present, the values ofslice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 are inferred to beequal to ph_cb_beta_offset_div2 and ph_cb_tc_offset_div2, respectively.

slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 specify thedeblocking parameter offsets for β and tC (divided by 2) that areapplied to the Cr component for the current slice. The values ofslice_cr_beta_offset_div2 and slice_cr_tc_offset_div2 shall both be inthe range of −12 to 12, inclusive. When not present, the values ofslice_cr_beta_offset_div2 and slice_cr_tc_offset_div2 are inferred to beequal to ph_cr_beta_offset_div2 and ph_cr_tc_offset_div2, respectively.

slice_ts_residual_coding_disabled_flag equal to 1 specifies that theresidual_coding( ) syntax structure is used to parse the residualsamples of a transform skip block for the current slice.slice_ts_residual_coding_disabled_flag equal to 0 specifies that theresidual_ts_coding( )syntax structure is used to parse the residualsamples of a transform skip block for the current slice. Whenslice_ts_residual_coding_disabled_flag is not present, it is infered tobe equal to 0.

slice_lmcs_enabled_flag equal to 1 specifies that luma mapping withchroma scaling is enabled for the current slice. slice_lmcs_enabled_flagequal to 0 specifies that luma mapping with chroma scaling is notenabled for the current slice. When slice_lmcs_enabled_flag is notpresent, it is inferred to be equal to 0.

slice_scaling_list_present_flag equal to 1 specifies that thescaling_list data used for the current slice is derived based on thescaling_list data contained in the referenced scaling_list APS withaps_params_type equal to SCALING_APS and adaptation_parameter_set_idequal to ph_scaling_list_aps_id. slice_scaling_list_present_flag equalto 0 specifies that the scaling_list data used for the current pictureis the default scaling_list data derived specified in clause 7.4.3.21.When not present, the value of slice_scaling_list_present_flag isinferred to be equal to 0.

The variable NumEntryPoints, which specifies the number of entry pointsin the current slice, is derived as follows:

NumEntryPoints = 0 for( i = 1; i < NumCtusInCurrSlice; i++ ) {  ctbAddrX= CtbAddrInCurrSlice[ i ] % PicWidthInCtbsY  ctbAddrY =CtbAddrInCurrSlice[ i ] / PicWidthInCtbsY (145)  prevCtbAddrX =CtbAddrInCurrSlice[ i − 1 ] % PicWidthInCtbsY  prevCtbAddrY =CtbAddrInCurrSlice[ i − 1 ] / PicWidthInCtbsY  if( CtbToTileRowBd[ctbAddrY ] != CtbToTileRowBd[  prevCtbAddrY ] | |    CtbToTileColBd[ctbAddrX ] != CtbToTileColBd[    prevCtbAddrX ] | |    ( ctbAddrY !=prevCtbAddrY &&    sps_wpp_entry_point_offsets_present_flag ) )  NumEntryPoints++ }

offset_len_minus1 plus 1 specifies the length, in bits, of theentry_point_offset_minus1[i] syntax elements. The value ofoffset_len_minus1 shall be in the range of 0 to 31, inclusive.

entry_point_offset_minus1[i] plus 1 specifies the i-th entry pointoffset in bytes, and is represented by offset_len_minus 1 plus 1 bits.The slice data that follow the slice header consists of NumEntryPoints+1subsets, with subset index values ranging from 0 to NumEntryPoints,inclusive. The first byte of the slice data is considered byte 0. Whenpresent, emulation prevention bytes that appear in the slice dataportion of the coded slice NAL unit are counted as part of the slicedata for purposes of subset identification. Subset 0 consists of bytes 0to entry_point_offset_minus1[0], inclusive, of the coded slice data,subset k, with k in the range of 1 to NumEntryPoints −1, inclusive,consists of bytes firstByte[k] to lastByte[k], inclusive, of the codedslice data with firstByte[k] and lastByte[k] defined as:

firstByte[k]=Σ_(n=1) ^(k)(entry_point_offset_minus1[n−1]+1)   (146)

lastByte[k]=firstByte[k]+entry_point_offset_minus1[k]  (147)

The last subset (with subset index equal to NumEntryPoints) consists ofthe remaining bytes of the coded slice data. Whensps_entropy_coding_sync_enabled_flag is equal to 0 and the slicecontains one or more complete tiles, each subset shall consist of allcoded bits of all CTUs in the slice that are within the same tile, andthe number of subsets (i.e., the value of NumEntryPoints+1) shall beequal to the number of tiles in the slice.

When sps_entropy_coding_sync_enabled_flag is equal to 0 and the slicecontains a subset of CTU rows from a single tile, the NumEntryPointsshall be 0, and the number of subsets shall be 1. The subset shallconsist of all coded bits of all CTUs in the slice.

When sps_entropy_coding_sync_enabled_flag is equal to 1, each subset kwith kin the range of 0 to NumEntryPoints, inclusive, shall consist ofall coded bits of all CTUs in a CTU row within a tile, and the number ofsubsets (i.e., the value of NumEntryPoints+1) shall be equal to thetotal number of tile-specific CTU rows in the slice.

slice_header_extension _length specifies the length of the slice headerextension data in bytes, not including the bits used for signallingslice_header_extension_length itself. The value ofslice_header_extension_length shall be in the range of 0 to 256,inclusive. When not present, the value of slice_header_extension_lengthis inferred to be equal to 0.

slice_header_extension_data_byte[i] may have any value. Decodersconforming to this version of this Specification shall ignore the valuesof all the slice_header_extension_data_byte[i] syntax elements. Itsvalue does not affect decoder conformance to profiles specified in thisversion of specification.

3.5. Chroma QP Mapping Table

In clause 7.3.2.3 of JVET-Q2001-vC, the SPS includes a structure namedchroma QP table, shown as follows:

Descriptor seq_parameter_set_rbsp( ) {  ......  if( ChromaArrayType != 0) {   sps _(—) joint _(—) cbcr _(—) enabled _(—) flag u(1)   same _(—)qp _(—) table _(—) for _(—) chroma u(1)   numQpTables =same_qp_table_for_chroma ? 1 : ( sps_joint_cbcr_enabled_flag ? 3 : 2 )  for( i = 0; i < numQpTables; i++ ) {    qp _(—) table _(—) start _(—)minus26[ i ] se(v)    num _(—) points _(—) in _(—) qp _(—) table _(—)minus1[ i ] ue(v)    for( j = 0; j <= num_points_in_qp_table_minus1[ i]; j++ ) {     delta _(—) qp _(—) in _(—) val _(—) minus1[ i ][ j ]ue(v)     delta _(—) qp _(—) diff _(—) val[ i ][ j ] ue(v)    }   }  }......

They are with the following semantics and QP table derivation:

sps_joint_cbcr_enabled_flag equal to 0 specifies that the joint codingof chroma residuals is disabled. sps_joint_cbcr_enabled_flag equal to 1specifies that the joint coding of chroma residuals is enabled. When notpresent, the value of spsjoint_cbcr_enabled_flag is inferred to be equalto 0.

same_qp_table_for_chroma equal to 1 specifies that only one chroma QPmapping table is signalled and this table applies to Cb and Cr residualsand additionally to joint Cb-Cr residuals whenspsjoint_cbcr_enabled_flag is equal to 1. same_qp_table_for_chroma equalto 0 specifies that chroma QP mapping tables, two for Cb and Cr, and oneadditional for joint Cb-Cr when sps_joint_cbcr_enabled_flag is equal to1, are signalled in the SPS. When same_qp_table_for_chroma is notpresent in the bitstream, the value of same_qp_table_for_chroma isinferred to be equal to 1.

qp_table_start_minus26[i] plus 26 specifies the starting luma and chromaQP used to describe the i-th chroma QP mapping table. The value ofqp_table_start_minus26[i] shall be in the range of −26—QpBdOffset to 36inclusive. When qp_table_start_minus26[i] is not present in thebitstream, the value of qp_table_start_minus26[i] is inferred to beequal to 0.

num_points_in_qp_table_minus1[i] plus 1 specifies the number of pointsused to describe the i-th chroma QP mapping table. The value ofnum_points_in_qp_table_minus1[i] shall be in the range of 0 to63+QpBdOffset, inclusive. When num_points_in_qp_table_minus1[0] is notpresent in the bitstream, the value of num_points_in_qp_table_minus1[0]is inferred to be equal to 0.

delta_qp_in_val_minus1[i][j] specifies a delta value used to derive theinput coordinate of the j-th pivot point of the i-th chroma QP mappingtable. When delta_qp_in_val_minus1[0][j] is not present in thebitstream, the value of delta_qp_in_val_minus1[0][j] is inferred to beequal to 0.

delta_qp_diff_val[i][j] specifies a delta value used to derive theoutput coordinate of the j-th pivot point of the i-th chroma QP mappingtable.

The i-th chroma QP mapping table ChromaQpTable [i] for i=0..numQpTables−1 is derived as follows:

qpInVal[ i ][ 0 ] = qp_table_start_minus26[ i ] + 26 qpOutVal[ i ][ 0 ]= qpInVal[ i ][ 0 ] for( j = 0; j <= num_points_in_qp_table_minus1[ i ];j++ ) {  qpInVal[ i ][ j + 1 ] = qpInVal[ i ][ j ] +delta_qp_in_val_minus1[  i ][ j ] + 1  qpOutVal[ i ][ j + 1 ] =qpOutVal[ i ][ j ] + ( delta_qp_in_val_minus1[ i ][ j ] {circumflex over( )} delta_qp_diff_val[ i ][ j ] ) } ChromaQpTable[ i ][ qpInVal[ i ][ 0] ] = qpOutVal[ i ][ 0 ] for( k = qpInVal[ i ][ 0 ] − 1; k >=−QpBdOffset; k − − )  ChromaQpTable[ i ][ k ] = Clip3( −QpBdOffset, 63, ChromaQpTable[ i ][ k + 1 ] − 1 ) for( j = 0; j <=num_points_in_qp_table_minus1[ i ]; j++ ) {  sh = (delta_qp_in_val_minus1[ i ][j ] + 1 ) >> 1  for( k = qpInVal[ i ][ j ] +1, m = 1; k <= qpInval[ i ][ j + 1 ]; k++,  m++ )   ChromaQpTable[ i ][k ] = ChromaQpTable[ i ][ qpInVal[ i ][ j ] ] +    ( ( qpOutVal[ i ][j +1] − qpOutVal[ i ][j ] ) * m + sh ) / ( delta_qp_in_val_minus1[ i ][j] +1 ) } for( k = qpInVal[ i ][ num_points_in_qp_table_minus1[ i ] + 1 ] +1; k <= 63; k++ )  ChromaQpTable[ i ][ k ] = Clip3( −QpBdOffset, 63, ChromaQpTable[ i ][ k − 1 ] + 1 )

When same_qp_table_for_chroma is equal to 1, ChromaQpTable[1][k] andChromaQpTable[2][k] are set equal to ChromaQpTable[0][k] for k in therange of −QpBdOffset to 63, inclusive.

It is a requirement of bitstream conformance that the values ofqpInVal[i][j] and qpOutVal[i][j] shall be in the range of −QpBdOffset to63, inclusive for i in the range of 0 to numQpTables −1, inclusive, andj in the range of 0 to num_points_in_qp_table_minus1[i]+1, inclusive.

In the above description, QpBdOffset is derived as:

bit_depth_minus8 specifies the bit depth of the samples of the luma andchroma arrays, BitDepth, and the value of the luma and chromaquantization parameter range offset, QpBdOffset, as follows:

BitDepth=8+bit_depth_minus8

QpBdOffset=6* bit_depth_minus8

bit_depth_minus8 shall be in the range of 0 to 8, inclusive.

4. Technical Problems Solved by Disclosed Technical Solutions

The existing designs in the latest VVC draft specification for APS,deblocking, subpicture, and QP delta have the following problems:

-   -   1) Currently, the value of the APS syntax element        scaling_list_chroma_present_flag is constrained based on        ChromaArrayType derived from SPS syntax elements        chroma_format_idc and separate_colour_plane_flag, phrased as        follows: scaling_list_chroma_present _flag shall be equal to 0        when ChromaArrayType is equal to 0, and shall be equal to 1 when        ChromaArrayType is not equal to 0.        -   Such constraints in the semantics of the APS syntax element            introduce semantics dependencies of APS on SPS, which should            not occur, because since there is no PPS ID or SPS ID in the            APS syntax, an APS may be applied to pictures (or slices of            pictures) that refer to different SPSs, which may be            associated with different values of ChromaArrayType.            -   a. Additionally, similar APS-SPS semantics dependencies                also exist in the semantics of some ALF/CC-ALF APS                syntax elements, phrased as follows: alf_chroma                _filter_signal _flag, alf_cc_cb_filter_signal _flag, and                alf_cc_cr _filter_signal _flag shall to be equal to 0                when ChromaArrayType is equal to 0.            -   b. Currently, when an LMCS_APS is signalled, the chroma                residual scaling related syntax elements are always                signalled in the LMCS_APS syntax structure, regardless                of whether ChromaArrayType is equal to 0 (i.e., there is                no chroma component in the CLVS). This results in                unnecessary signalling of chroma-related syntax                elements.    -   2) It is asserted that the deblocking control mechanism in the        latest VVC text is pretty complicated, not straightforward, and        not easy to understand, and consequently prone to errors. Here        are some example issues we observed:        -   a. According to the current text, even if the deblocking            filter is disabled in the PPS, it can be enabled in the PH            or SH. For example, if pps_deblocking_filter_disabled_flag            is firstly signalled to be equal to 1, and            deblocking_filter_override_enabled_flag is also signalled to            be equal to 1, it indicates that the deblocking filter is            disabled at PPS and it also allows the deblocking_filter            enable/disable control being overridden in the PH or SH.            Then dbf_info_in_ph_flag is signalled subsequently and the            PH syntax element ph_deblocking_filter_disabled_flag might            be signalled to be equal to 0 which ultimately enables the            deblocking_filter for slices associated with the PH. In such            case, the deblocking is eventually enabled at PH regardless            that it has been disabled at the higher level (e.g., PPS).            Such design logic is unique in VVC text, and it is quite            different from the design logic of other coding tools (e.g.,            ALF, SAO, LMCS, TMVP, WP, and etc.) as normally when a            coding tool is disabled at a higher layer (e.g., SPS, PPS),            then it is disabled completely at lower layers (e.g., PH,            SH).        -   b. Furthermore, the current definition of            pps_deblocking_filter_disabled_flag is like “pps_deblocking            _filter_disabled _flag equal to 1 specifies that the            operation of deblocking filter is not applied for slices            referring to the PPS in which slice_deblocking            _filter_disabled _flag is not present . . . ”. However,            according to the current syntax table, even though            pps_deblocking_filter_disabled_flag is equal to 1 and slice            deblocking_filter_disabled_flag is not present, the            operation of deblocking filter would still be applied in            case of ph_deblocking_filter_disabled_flag is present and            signalled to be equal to 0. Therefore, the current            definition of pps_deblocking_filter_disabled_flag is not            correct.        -   c. Moreover, according to the current text, if both the PPS            syntax elements deblocking_filter_override_enabled_flag and            pps_deblocking_filter_disabled_flag are equal to 1, it            specifies that deblocking is disabled in PPS and the control            of deblocking filter is intended to be overridden in the PH            or SH. However, the subsequent PH syntax elements            ph_deblocking_filter_override_flag and            ph_deblocking_filter_disabled_flag might be still signalled            to be equal to 1, which turns out that the resulted            overriding process doesn't change anything (e.g., deblocking            remains disabled in the PH/SH) but just use unnecessary bits            for meaningless signalling.        -   d. In addition, according to the current text, when the SH            syntax element slice_deblocking_filter_override_flag is not            present, it is inferred to be equal to            ph_deblocking_filter_override_flag. However, besides            implicit or explicit signalling in the PPS, the deblocking            parameters can only be signalled either in PH or SH            according to dbf_info_in_ph_flag, but never both. Therefore,            when dbf_info_in_ph_flag is true, the intention is to allow            to signal the overriding deblocking_filter parameters in the            PH. In this case, if the PH override flag is true and the SH            override flag is not signalled but inferred to be equal to            the PH override flag, additional deblocking_filter            parameters will still be signalled in the SH which is            conflicting with the intention.        -   e. In addition, there is no SPS-level deblocking on/off            control, which may be added and the related syntax elements            in PPS/PH/SH may be updated accordingly.    -   3) Currently, when the PPS syntax element        single_slice_per_subpic_flag is not present, it is inferred to        be equal to 0. single_slice_per_subpic_flag is not present in        two cases: i) no_pic_partition_flag is equal to 1, and ii)        no_pic_partition_flag is equal to 0 and rect slice flag is equal        to 0.        -   For case i), no_pic_partition_flag equal to 1 specifies that            no picture partitioning is applied to each picture referring            to the PPS, therefore, there is only one slice in each            picture, and consequently, there is only one subpicture in            each picture and there is only one slice in each subpicture.            Therefore, in this case single_slice_per_subpic_flag should            be inferred to be equal 1.        -   For case ii), since rect slice flag is equal to 0, an            inferred value of single_slice_per_subpic_flag is not            needed.    -   4) Currently, luma qp delta in either picture or slice level is        always signalled mandatorily, either in the PH or SH, never        both. Whereas the slice-level chroma QP offset is optionally        signalled in the SH. Such design is somewhat not consistent.        -   a. Additionally, the current semantics of the PPS syntax            element cu_qp_delta_enabled_flag is worded as follows:            cu_qp_delta_enabled_flag equal to 1 specifies that the            ph_cu_qp_delta_subdiv_intra_slice and            ph_cu_qp_delta_subdiv_inter_slice syntax elements are            present in PHs referring to the PPS and cu qp delta abs may            be present in the transform unit syntax . . . However,            cu_qp_delta_abs may be also present in the palette coding            syntax, which should also be specified by            cu_qp_delta_enabled_flag. In other words, the current            semantics of cu_qp_delta_enabled_flag is not clear enough            and a bit confusing.    -   5) The current design of chroma Qp mapping table is not        straightforward to represent the case of chroma Qp equal to luma        Qp.    -   6) Currently, the subpic_treated_as_pic_flag[i] is inferred to        be equal to the value of sps_independent_subpics_flag. However,        the current spec only allows the horizontal wrap-around to be        enabled when subpic_treated_as_pic flag[i] is equal to 0,        wherein the wrap-around motion compensation is designed for 360        video content. Therefore, when a pictures contains only one        subpicture (especially for the case that a complete 360 video        sequence contains only one subpicture), the inferred value for        subpic_treated_as_pic flag[i] may be inferred to be equal to 0        or a certain value that allows the wrap-around motion        compensation.

5. A Listing of Solutions and Embodiments

To solve the above problems and some other problems not mentioned,methods as summarized below are disclosed. The items listed below shouldbe considered as examples to explain the general concepts and should notbe interpreted in a narrow way. Furthermore, these items can be appliedindividually or combined in any manner.

In the following discussion, an SH may be associated with a PH, i.e.,the SH is associated with a slice, which is in the picture associatedwith the PH. An SH may be associated with a PPS, i.e., the SH isassociated with a slice, which is in the picture associated with thePPS. A PH may be associated with a PPS, i.e., the PH is associated witha picture, which is associated with the PPS.

In the following discussion, a SPS may be associated with a PPS, i.e.,the PPS may refer to the SPS.

In the following discussion, the changed texts are based on the latestVVC text in JVET-Q2001-vE. Most relevant parts that have been added ormodified are

, italics, and some of the deleted parts are marked with the doublebracket (e.g., [[a]] denotes the deletion of the character ‘a’).

-   1. Regarding the constraints on APS syntax elements for solving the    first problem, one or more of the following approaches are    disclosed:    -   a. In one example, constrain the value of        scaling_list_chroma_present_flag according to ChromaArrayType        derived by the PH syntax element.        -   i. For example, whether the value of            scaling_list_chroma_present_flag is constrained or not may            be dependent on whether ph_scaling_list_aps_id is present or            not, e.g., as in the first set of embodiments.            -   1) In one example, it is required that, when                ph_scaling_list_aps_id is present, the value of                scaling_list_chroma_present_flag of the APS NAL unit                having aps_params_type equal to SCALING APS and                adaptation_parameter_set_id equal to                ph_scaling_list_aps_id shall be equal to                ChromaArrayType==0? 0 :1.        -   ii. Alternatively, scaling_list_chroma_present_flag is            constrained based on ChromaArrayType derived by the PH            syntax elements, but regardless of the presence of            ph_scaling_list_aps_id, e.g., as in the first set of            embodiments.            -   1) In one example, it is required that, the value of                scaling_list_chroma_present_flag of the APS NAL unit                having aps_params_type equal to SCALING APS shall be                equal to ChromaArrayType==0? 0 : 1.    -   b. In one example, constrain the value of lmcs_delta_abs_crs        according to ChromaArrayType derived by the PH syntax element.        -   i. For example, whether the value of lmcs_delta_abs_crs is            constrained or not may be dependent on whether            ph_lmcs_aps_id is present or not, e.g., as in the first set            of embodiments.            -   1) For example, it is required that, when ph_lmcs_aps_id                is present, the value of lmcs_delta_abs_crs of the APS                NAL unit having aps_params_type equal to LMCS_APS and                adaptation_parameter_set_id equal to ph_lmcs_aps_id                shall be equal to 0 if ChromaArrayType is equal to 0 and                shall be greater than 0 otherwise.            -   2) Alternatively, it is required that, when                ph_lmcs_aps_id is present, the value of                lmcs_delta_abs_crs of the APS NAL unit having                aps_params_type equal to LMCS_APS and                adaptation_parameter_set_id equal to ph_lmcs_aps_id                shall be equal to 0 if ChromaArrayType is equal to 0.        -   ii. Alternatively, lmcs_delta_abs_crs is constrained based            on ChromaArrayType derived by the PH syntax elements, but            regardless of the presence of ph_lmcs_aps_id, e.g., as in            the first set of embodiments.            -   1) For example, it is required that, the value of                lmcs_delta_abs_crs of the APS NAL unit equal to                ph_lmcs_aps_id shall be equal to 0 if ChromaArrayType is                equal to 0 and shall be greater than 0 otherwise.            -   2) For example, it is required that, the value of                lmcs_delta_abs_crs of the APS NAL unit equal to                ph_lmcs_aps_id shall be equal to 0 if ChromaArrayType is                equal to 0.    -   c. In one example, constrain the value of ALF APS syntax        elements (e.g., alf_chroma_filter_signal flag,        alf_cc_cb_filter_signal_flag, alf_cc_cr_filter_signal_flag, and        etc.) according to ChromaArrayType derived by the PH syntax        elements and/or the SH syntax elements.        -   i. For example, whether the value of            alf_chroma_filter_signal_flag and/or            alf_cc_cb_filter_signal_flag and/or            alf_cc_cr_filter_signal_flag are constrained or not may be            dependent on whether ph_alf_aps_id_luma[i] or            slice_alf_aps_id_luma[i] is present or not and/or whether            ChromaArrayType is equal to 0 or not, e.g., as in the first            set of embodiments.            -   1) For example, it is required that, when                ph_alf_aps_id_luma[i] is present and ChromaArrayType is                equal to 0, the values of alf_chroma_filter_signal_flag,                alf_cc_cb_filter_signal_flag, and                alf_cc_cr_filter_signal_flag of the APS NAL unit having                aps_params_type equal to ALF APS and                adaptation_parameter_set_id equal to                ph_alf_aps_id_luma[i] shall all be equal to 0.            -   2) Additionally, it is required that, when                slice_alf_aps_id_luma[i] is present and ChromaArrayType                is equal to 0, the values of                alf_chroma_filter_signal_flag,                alf_cc_cb_filter_signal_flag, and                alf_cc_cr_filter_signal_flag of the APS NAL unit having                aps_params_type equal to ALF APS and                adaptation_parameter_set_id equal to                slice_alf_aps_id_luma[i] shall all be equal to 0.        -   ii. Altenatively, alf_chroma_filter_signal_flag and/or            alf_cc_cb_filter_signal_flag and/or            alf_cc_cr_filter_signal_flag are constrained based on            ChromaArrayType derived by the PH syntax elements or SH            syntax elements, but regardless of the presence of            ph_alf_aps_id_luma[i] and/or slice_alf_aps_id_luma[i], e.g.,            as in the first set of embodiments.            -   1) For example, it is required that, when                ChromaArrayType is equal to 0, the values of                alf_chroma_filter_signal_flag,                alf_cc_cb_filter_signal_flag, and                alf_cc_cr_filter_signal_flag of the APS NAL unit having                aps_params_type equal to ALF_APS shall all be equal to                0.            -   2) Additionally, it is required that, when                ChromaArrayType is equal to 0, the values of                alf_chroma_filter_signal_flag,                alf_cc_cb_filter_signal_flag, and                alf_cc_cr_filter_signal_flag of the APS NAL unit having                aps_params_type equal to ALF_APS shall all be equal to                0.        -   iii. Altenatively, alf_chroma_filter_signal_flag and/or            alf_cc_cb_filter_signal_flag and/or            alf_cc_cr_filter_signal_flag are constrained based on            ChromaArrayType derived by the chroma APS ID related PH or            SH syntax elements, e.g., as in the first set of            embodiments.            -   1) For example , alf_chroma_filter_signal_flag is                constrained according to ChromaArrayType derived by the                PH syntax element ph_alf_aps_id chroma and/or the SH                syntax element slice_alf_aps_id_chroma.            -   2) For example, alf_cc_cb_filter_signal_flag is                constrained according to ChromaArrayType derived by the                PH syntax element ph_cc_alf_cb_aps_id and/or the SH                syntax element slice_cc_alf_cb_aps_id.            -   3) For example, alf_cc_cr_filter_signal_flag is                constrained according to ChromaArrayType derived by the                PH syntax element ph_cr_alf_cb_aps_id and/or the SH                syntax element slice_cr_alf_cb_aps_id.    -   d. In one example, the semantics of APS syntax elements in the        ALF and/or SCALING LIST and/or LMCS data syntax structure may be        not dependent on whether it is 4:0:0 video coding and/or        separate color plane coding.        -   i. For example, the semantics of APS syntax elements in the            ALF data syntax structure (e.g.,            alf_chroma_filter_signal_flag, alf_cc_cb_filter_signal_flag,            alf_cc_cr_filter_signal_flag, and etc.) may be not dependent            on variables/syntaxes derived by SPS/PH/SH syntax elements            (e.g., ChromaArrayType), e.g., as in the first set of            embodiments.        -   ii. Additionally, alternatively, the semantics of APS syntax            elements in the SCALING LIST data syntax structure (e.g.,            scaling_list_chroma_present_flag, and etc.) may be not            dependent on variables/syntaxes derived by SPS/PH/SH syntax            elements (e.g., ChromaArrayType) , e.g., as in the first set            of embodiments.    -   e. Additionally, whether the temporand of the ALF/SCALING/LMCS        APS NAL unit is constrained or not may be dependent on whether        the corresonding APS ID is present or not, e.g., as in the first        set of embodiments.        -   i. For example, whether the temporand of the ALF APS NAL            unit is constrained or not may be dependent on whether            ph_alf_aps_id_luma[i] and/or ph_alf_aps_id_chroma and/or            ph_cc_alf_cb_aps_id and/or ph_cc_alf_cr_aps_id is present or            not.        -   ii. For example, whether the temporand of the LMCS APS NAL            unit is constrained or not may be dependent on whether            ph_lmcs_aps_id is present or not.        -   iii. For example, whether the temporand of the SCALING APS            NAL unit is constrained or not may be dependent on whether            ph_scaling_list_aps_id is present or not.    -   f. Additionally, whether the values of        alf_luma_filter_signal_flag, alf_chroma_filter_signal_flag        and/or alf_cc_cb_filter_signal_flag and/or        alf_cc_cr_filter_signal_flag shall be equal to 1 may be        dependent on whether the corresponding APS ID is present or not,        e.g., as in the first set of embodiments.        -   i. For example, whether alf_luma_filter_signal_flag shall be            equal to 1 or not may be dependent on whether            ph_alf_aps_id_luma[i] and/or slice_alf_aps_id_luma[i] is            present or not.        -   ii. For example, whether alf_chroma_filter_signal_flag shall            be equal to 1 or not may be dependent on whether            ph_alf_aps_id_chroma and/or slice_alf_aps_id_chroma is            present or not.        -   iii. For example, whether alf_cc_cb_filter_signal_flag shall            be equal to 1 or not may be dependent on whether            ph_cc_alf_cb_aps_id and/or slice_cc_alf_cb_aps_id is present            or not.        -   iv. For example, whether alf_cc_cr_filter_signal_flag shall            be equal to 1 or not may be dependent on whether            ph_cc_alf_cr_aps_id and/or slice_cc_alf_cr_aps_id is present            or not.    -   g. Additionally, alternatively, whether the chroma ALF APS ID        syntax elements in the SH (e.g., slice_alf_aps_id_chroma, slice        cc_alf_cb_aps_id, slice_cr_alf_cb_aps_id, and etc.) in inferred        or not may be dependent on the value of ChromaArrayType, e.g.,        as in the first set of embodiments.        -   i. For example, when ChromaArrayType is not equal to 0, the            value of the chroma ALF APS ID syntax elements in the SH            (e.g., slice_alf_aps_id_chroma, slice cc_alf_cb_aps_id,            slice_cr_alf_cb_aps_id, and etc.) may be inferred.-   2. Regarding the signalling of deblocking control for solving the    second problem, one or more of the following approaches are    disclosed, e.g., as in the second set of embodiments:    -   a. In one example, an N-bit (such as N=2) deblocking mode        indicator (e.g., named deblocking_filter_mode_idc) is signalled.        -   i. In one example, the syntax element            deblocking_filter_mode_idc is u(2) coded.            -   a) Alternatively, the parsing process of                deblocking_filter_mode_idc is unsigned integer with N                (such as N=2) bits.        -   ii. In one example, the syntax element            deblocking_filter_mode_idc is signalled in the PPS.        -   iii. In one example, the syntax element            deblocking_filter_mode_idc is used to specify the following            four modes: a) deblocking fully disabled and not used for            all slices; b) deblocking used for all slices using 0-valued            β and tC offsets; c) deblocking used for all slices using β            and tC offsets explicitly signalled in the PPS; and d)            deblocking further controlled at either picture or slice            level.    -   b. A syntax flag ph/slice_deblocking_filter_used_flag is        signalled either in the PH or SH, specifying whether deblocking        is used for the current picture/slice.    -   c. A syntax flag ph/slice_deblocking_parameters_override_flag is        signalled either in the PH or SH, specifying whether the β and        tC offsets are overridden by the values signalled in the PH/SH.        -   i. Additionally, infer the value of            slice_deblocking_parameters_override_flag to be equal to 0            when not present.    -   d. In one example, the syntax elements specifying the deblocking        control (e.g., enable flag, disable flag, control flag,        deblocking mode indicator, deblocking_filter beta/tc parameters,        and etc.) may be signalled in the SPS.        -   i. In one example, one or more syntax elements may be            signalled in the SPS specifying whether the deblocking is            enabled or not in the video unit (e.g., CLVS).        -   ii. Additionally, when the deblocking is disabled in the            SPS, it is required that the syntax element in the PPS/PH/SH            regarding the deblocking on/off control at PPS/PH/SH level            shall be equal to a certain value that specifying the            deblocking is fully disabled and not used for all slices.        -   iii. In one example, the deblocking filter control present            flag may be signalled in the SPS.        -   iv. For example, an N-bit (such as N=2) deblocking mode            indicator (e.g., named deblocking_filter_mode_idc) may be            signalled in the SPS.        -   v. For example, beta/tc deblocking parameters may be            signalled in the SPS.        -   vi. For example, whether the deblocking is enabled with            0-valued beta/tc deblocking parameters may be dependent on            the SPS syntax element.        -   vii. For example, the deblocking may be applied at the            SPS/PPS/PH/SH level and use the beta/tc deblocking            parameters signalled in the SPS.        -   viii. For example, the deblocking may be applied at the            SPS/PPS/PH/SH level and use the 0-valued deblocking            parameters signalled in the SPS.-   3. Regarding the inference of the PPS syntax element    single_slice_per_subpic_flag for solving the third problem, one or    more of the following approaches are disclosed:    -   a. In one example, infer single_slice_per_subpic flag to be        equal to 1 when no_pic_partition_flag is equal to 1, e.g., the        semantics of single_slice_per_subpic_flag is changed as follows:        -   single_slice_per_subpic_flag equal to 1 specifies that each            subpicture consists of one and only one rectangular slice.            single_slice_per_subpic_flag equal to 0 specifies that each            subpicture may consist of one or more rectangular slices.            When            [[not present]], the value of single_slice_per_subpic_flag            is inferred to be equal to [[0]]            .-   4. Regarding the picture or slice QP delta signalling for solving    the fourth problem, one or more of the following approaches are    disclosed:    -   a. In one example, picture or slice level chroma QP offset are        always signalled, either in the PH or SH.        -   i. For example, if there is chroma component in the video            content (e.g., ChromaArrayType is not equal to 0), picture            or slice level chroma QP offset may be always signalled,            without conditioned on the present flag signalled in the PPS            (e.g., pps_slice_chroma_qp_offsets_present_flag).        -   ii. Alternatively, if there is chroma component in the video            content (e.g., ChromaArrayType is not equal to 0),            slice_cb_qp_offset and slice_cr_qp_offset syntax elements            may be always present in the associated slice headers,            regardless the PPS present flag (e.g.,            pps_slice_chroma_qp_offsets_present_flag).        -   iii. Additionally, the present flag (e.g.,            pps_slice_chroma_qp_offsets_present_flag) specifying the            presence of slice_cb_qp_offset and slice_cr_qp_offset syntax            elements, may be not signalled.    -   b. In one example, pps_cu_qp_delta_enabled_flag may be used to        specify the presence of cu_qp_delta_abs and        cu_qp_delta_sign_flag in both the transform unit syntax and the        palette coding syntax, and the semantics of        pps_cu_qp_delta_enabled_flag are changed as follows:        -   _cu_qp_delta_enabled_flag equal to 1 specifies that the            ph_cu_qp_delta_subdiv_intra_slice and            ph_cu_qp_delta_subdiv_inter_slice syntax elements are            present in PHs referring to the PPS, and            cu_qp_delta_abs            may be present in the transform unit syntax            pps_cu_qp_delta_enabled_flag equal to 0 specifies that the            ph_cu_qp_delta_subdiv_intra_slice and            ph_cu_qp_delta_subdiv_inter_slice syntax elements are not            present in PHs referring to the PPS, and            cu_qp_delta_abs            [[is]] not present in the transform unit syntax            .    -   c. In one example, the luma QP delta may be signalled in both        the PH and the SH.        -   i. For example, luma QP delta present flag may be signalled            in the PPS and/or PH, and/or the SH.        -   ii. For example, whether the luma QP delta is signalled in            PH/SH is dependent on the present flags in the PPS and/or            PH/SH.        -   iii. For example, the values of the PH luma QP delta and the            SH luma QP delta may be additive and used for calculating            the luma quantization parameter such as SliceQpy.    -   d. In one example, the chroma QP offsets may be signalled in        both the PH and the SH.        -   i. For example, chroma QP offsets present flag may be            signalled in the PPS and/or PH, and/or the SH.        -   ii. For example, whether the chroma QP offsets are signalled            in PH/SH is dependent on the present flags in the PPS and/or            PH/SH.        -   iii. For example, the values of the PH chroma QP offsets and            the SH chroma QP offsets may be additive and used for            deriving the chroma quantization parameter for the Cb and Cr            components.-   5. Regarding the chroma Qp mapping tables, one or more of the    following approaches are disclosed:    -   a. In one example, in the derivation process of the chroma QP        table, the XOR operator should be performed between        (delta_qp_in_val_minus1[i][j]+1) and delta_qp_ diff_val[i][j],        e.g. as in the third set of embodiment.    -   b. It is proposed to have a flag in        sps_multiple_sets_of_chroma_qp_table_present_flag in SPS.        -   i. When sps_multiple_sets_of_chroma_qp_table_present_flag is            equal to 0, only one set of chroma Qp mapping table is            allowed to be signalled.        -   ii. When sps_multiple_sets_of_chroma_qp_table_present_flag            is equal to 1, more than one set of chroma Qp mapping table            are allowed to be signalled.    -   c. More than one set of chroma Qp mapping tables may be        disallowed to be signalled for a sequence without B/P slices.-   6. Regarding the sps_independent_subpics_flag and    subpic_treated_as_pic_flag[i] for solving the sixth problem, one or    more of the following approaches are disclosed:    -   a. In one example, the presence of sps_independent_subpics_flag        is dependent on whether the number of subpictures is greater        than 1.        -   i. For example, only when the number of subpictures is            greater than 1 (e.g., if (sps_num_subpics_minus1>0)),            sps_independent_subpics_flag_is_signalled.        -   _ii._For_example,_when_the_number of subpictures is equal to            1 (e.g., if (sps_num_subpics_minus1==0)), then the            signalling of sps_independent_subpics_flag is skipped.    -   b. Additionally, when sps_independent_subpics_flag is not        present, it is inferred to be equal to a certain value (such as        0 or 1).    -   c. In one example, when subpic_treated_as_pic_flag[i] is not        present, it is inferred to be equal to a certain value (such as        0 or 1).    -   d. In one example, when subpic_treated_as_pic_flag[i] is not        present, it is inferred to be equal to a certain value wherein        the wrap-around motion compensation is enabled (or may be used).        -   i. Additionally, when subpic_treated_as_pic_flag[i] is not            present, it is inferred to be equal to a certain value            wherein the horizontal wrap-around motion compensation is            enabled (or may be used).    -   e. In one example, the inferred value of        subpic_treated_as_pic_flag[i] may be dependent on whether a        picture only consists of one subpicture; and/or whether the        subpicture has the same width as the picture.        -   i. In one example, if the subpicture has the same width as            the picture, subpic_treated_as_pic_flag[i] may be inferred            to X (e.g., X=0).    -   f. In one example, when sps_independent_subpics_flag is not        present, what value that sps_independent_subpics_flag is        inferred to may be dependent on other syntax element(s) or        variable(s).        -   i. For example, the inferred value may depend on whether the            subpicture information is present or not (e.g.,            subpic_info_present_flag is equal to 0 or 1).        -   ii. For example, when subpic_info_present_flag is equal to 0            and sps_independent_subpics_flag is not present, it is            inferred to be equal to a certain value (such as 0 or 1).        -   iii. For example, when subpic_info_present_flag is equal to            1 and sps_independent_subpics_flag is not present, it is            inferred to be equal to a certain value (such as 0 or 1).    -   g. In one example, when subpic_treated_as_pic_flag[i] is not        present, what value that subpic_treated_as_pic_flag[i] is        inferred to may be dependent on the presence of subpicture        information (e.g., subpic info_present_flag) and/or the number        of subpictures in the CLVS (e.g., sps_num_subpics_minus1) and/or        sps_independent_subpics_flag.        -   i. In one example, when subpic_info_present_flag is equal to            0, and subpic_treated_as_pic_flag[i] is not present, the            value of subpic_treated_as_pic_flag[i] is inferred to be            equal to a certain value (such as 0).        -   ii. In one example, when subpic_info_present_flag is equal            to 1, and subpic_treated_as_pic_flag[i] is not present, the            value of subpic_treated_as_pic_flag[i] is inferred to be            equal to a certain value (such as 1).        -   iii. In one example, when subpic_info_present_flag is equal            to 1, and sps_num_subpics_minus1 is equal to 0, and            subpic_treated_as_pic_flag[i] is not present, the value of            subpic_treated_as_pic_flag[i] is inferred to be equal to a            certain value (such as 0 or 1).        -   iv. In one example, when subpic_info_present_flag is equal            to 1, sps_num_subpics_minus1 is greater than 0,            sps_independent_subpics_flag is equal to 1, and            subpic_treated_as_pic_flag[i] is not present, the value of            subpic_treated_as_pic_flag[i] is inferred to be equal to a            certain value (such as 0 or 1).-   7. How to do padding or clipping on a boundary during the    inter-prediction process may depend on a combined checking of the    type of boundary, the indication of wrap around padding or clipping    (e.g. pps_ref_wraparound_enabled_flag,    sps_ref_wraparound_enabled_flag, and etc.) and the indication of    treating subpicture boundary as picture boundary (e.g.    subpic_treated_as_pic_flag[i]).    -   a. For example, if a boundary is a picture boundary, the        indication of wrap around padding is true, wrap around padding        (or wrap around clipping) may be applied, without considering        the indication of treating subpicture boundary as picture        boundary.        -   i. In one example, the boundary must be a vertical boundary.    -   b. For example, if both two vertical boundaries are picture        boundaries, the indication of wrap around padding is true, wrap        around padding (or wrap around clipping) may be applied, without        considering the indication of treating subpicture boundary as        picture boundary.    -   c. In one example, the above wrap around padding (or wrap around        clipping) may indicate horizontal wrap-around padding/clipping.-   8. In one example, different indications for wrap around padding or    clipping may be signaled for different subpictures.-   9. In one example, different offsets for wrap around padding or    clipping may be signaled for different subpictures.-   10. In the PH/SH, a variable X is used to indicate whether B slice    is allowed/used in a picture/slice, and the variable may be derived    using one of the following ways: a) (rpl_info_in_ph_flag &&    num_ref_entries[0][RplsIdx[0]]>0 &&    num_ref_entries[1][RplsIdx[1]]>0); b) (rpl_info_in_ph_flag &&    num_ref_entries[1][RplsIdx[1]]>0); c) (rpl_info_in_ph_flag &&    num_ref_entries[1][RplsIdx[1]]>1); d) (rpl_info_in_ph_flag &&    num_ref_entries[1][RplsIdx[1]]>0); e) based on NumRefIdxActive    (e.g., NumRefIdxActive for list 1 greater than K (e.g., K=0)) in the    VVC text; f) based on number of allowed reference pictures for list    1.    -   1) Alternatively, furthermore, signalling and/or semantics        and/or inference of one or multiple syntax elements signalled in        PH may be modified according to the variable.        -   i. In one example, the one or multiple syntax elements are            those for enabling a coding tool which requires more than            one prediction signal, such as bi-prediction or mixed intra            and inter coding, or prediction with linear/non-linear            weighting from multiple prediction blocks.        -   ii. In one example, the one or multiple syntax elements may            include, but not limited to:            -   a) ph_collocated_from_10_flag            -   b) mvd_11_zero_flag            -   c) ph_disable_bdof_flag            -   d) ph_disable_dmvr_flag            -   e) num_11_weights        -   iii. In one example, only when the variable indicates that            the picture may contain one or more B slices, the one or            multiple syntax elements may be signalled. Otherwise, the            signalling is skipped, and the values of the syntax element            are inferred.            -   a) Alternatively, furthermore, whether to signal the one                or more syntax elements may depend on the variable X                such as (X being true or 1).            -   b) ph_disable_bdof_flag may be signalled only when                (sps_bdof_pic_present flag                ) is true.            -   c) ph_disable_dmvr_flag may be signalled only when                (sps_dmvr_pic_present_flag                ) is true.        -   iv. In one example, when X is equal to 0 (or false),            mvd_11_zero_flag is not signalled, and its values is            inferred to be 1.        -   v. In one example, the inference of the one or multiple            syntax elements are dependent on the value of the variable            X.            -   a) In one example, for the ph_disable_bdof_flag, the                following applies:                -   If sps_bdof_enabled_flag is equal to 1                    , the value of ph_disable_bdof_flag is inferred to                    be equal to 0.                -   Otherwise (sps_bdof_enabled_flag is equal to 0                    , the value of ph_disable_bdof_flag is inferred to                    be equal to 1.            -   b) In one example, for the ph_disable_dmvr_flag, the                following applies:                -   If sps_dmvr_enabled_flag is equal to 1                    , the value of ph_disable_dmvr_flag is inferred to                    be equal to 0.                -   Otherwise (sps_dmvr_enabled_flag is equal to 0                    , the value of ph_disable_dmvr_flag is inferred to                    be equal to 1.            -   c) In one example, when ph_temporal_mvp_enabled_flag and                rpl_info_in_ph_flag are both equal to 1 and X is equal                to 0 (or false), the value of ph_collocated_from_10_flag                is inferred to be equal to 1.            -   d) In one example, when X is equal to 0 (or false),                num_11_weights is not signalled and its value is                inferred to be 0, and, consequently, weighted prediction                parameters for reference picture list 1 are not                signalled in the PH or SHs of the picture.

6. Example Embodiments

Below are some example embodiments for some of the aspects summarizedabove in Section 5, which can be applied to the VVC specification. Thechanged texts are based on the latest VVC text in JVET-Q2001-vE. Mostrelevant parts that have been added or modified are

and some of the deleted parts are marked with the double bracket (e.g.,[[a]] denotes the deletion of the character ‘a’).

6.1. First Set of Embodiments

This is a set of embodiments for items 1 summarized above in Section 5.

6.1.1. An Embodiment for 1.a.i

ph_scaling_list_aps_id specifies the adaptation_parameter_set_id of thescaling_list APS.

The TemporalId of the APS NAL unit having aps_params_type equal toSCALING_APS and adaptation_parameter_set_id equal toph_scaling_list_aps_id shall be less than or equal to the TemporalId ofthe picture associated with PH.

scaling_list_chroma_present_flag equal to 1 specifies that chromascaling_lists are present in scaling_list_data( )scaling_list_chroma_present_flag equal to 0 specifies that chromascaling_lists are not present in scaling_list_data( ) [[It is arequirement of bitstream conformance thatscaling_list_chroma_present_flag shall be equal to 0 whenChromaArrayType is equal to 0, and shall be equal to 1 whenChromaArrayType is not equal to 0.]]

6.1.2. An Embodiment for 1.a.ii

ph_scaling_list_aps_id specifies the adaptation_parameter_set_id of thescaling_list APS.

The TemporalId of the APS NAL unit having aps_params_type equal toSCALING_APS and adaptation_parameter_set_id equal toph_scaling_list_aps_id shall be less than or equal to the TemporalId ofthe picture associated with PH.

(alternatively, it may be phrased as follows:

scaling_list_chroma_present_flag equal to 1 specifies that chromascaling_lists are present in scaling_list_data( )scaling_list_chroma_present_flag equal to 0 specifies that chromascaling_lists are not present in scaling_list_data( ) [[It is arequirement of bitstream conformance thatscaling_list_chroma_present_flag shall be equal to 0 whenChromaArrayType is equal to 0, and shall be equal to 1 whenChromaArrayType is not equal to 0.]]

6.1.3. An Embodiment for 1.b.i

ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the LMCS APSthat the slices associated with the PH refers to.

The TemporalId of the APS NAL unit having aps_params_type equal toLMCS_APS and adaptation_parameter_set_id equal to ph_lmcs_aps_id shallbe less than or equal to the TemporalId of the picture associated withPH.

6.1.4. An Embodiment for 1.b.ii

ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the LMCS APSthat the slices associated with the PH refers to.

The TemporalId of the APS NAL unit having aps_params_type equal toLMCS_APS and adaptation_parameter_set_id equal to ph_lmcs_aps_id shallbe less than or equal to the TemporalId of the picture associated withPH.

6.1.5. An Embodiment for 1.c.i

The semantics of PH syntax elements are changes as follows:

ph_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of thei-th ALF APS that the luma component of the slices associated with thePH refers to.

The value of alf_luma_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto ph_alf_aps_id_luma[i] shall be equal to 1.

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i]shall be less than or equal to the TemporalId of the picture associatedwith the PH.

The semantics of SH syntax elements are changes as follows:

slice_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id ofthe i-th ALF APS that the luma component of the slice refers to. Whenslice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_luma[i] is notpresent, the value of slice_alf_aps_id_luma[i] is inferred to be equalto the value of ph_alf_aps_id_luma[i].

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal toslice_alf_aps_id_luma[i] shall be less than or equal to the TemporalIdof the coded slice NAL unit. The value of alf_luma_filter_signal_flag ofthe APS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_alf_aps_id_luma[i] shall beequal to 1.

And the semantics of the APS syntax elements in the ALF data syntaxstructure are changed as follows:

alf_chroma_filter_signal_flag equal to 1 specifies that a chroma filteris signalled. alf_chroma_filter_signal_flag equal to 0 specifies that achroma filter is not signalled. [[When ChromaArrayType is equal to 0,alf_chroma_filter_signal_flag shall be equal to 0.]]

alf_cc_cb_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cb colour component are signalled.alf_cc_cb_filter_signal_flag equal to 0 specifies that cross-componentfilters for Cb colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cb_filter_signal_flag shall beequal to 0.]]

alf_cc_cr_ffiter_signal_flag equal to 1 specifies that cross-componentfilters for the Cr colour component are signalled.alf_cc_cr_filter_signal_flag equal to 0 specifies that cross-componentfilters for the Cr colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cr_filter_signal_flag shall beequal to 0.]]

6.1.6. An Embodiment for 1.c.ii

The semantics of PH syntax elements are changes as follows:

ph_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of thei-th ALF APS that the luma component of the slices associated with thePH refers to.

The value of alf_luma_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto ph_alf_aps_id_luma[i] shall be equal to 1.

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i]shall be less than or equal to the TemporalId of the picture associatedwith the PH.

ph_alf_chroma_idc equal to 0 specifies that the adaptive loop filter isnot applied to Cb and Cr colour components. ph_alf_chroma_idc equal to 1indicates that the adaptive loop filter is applied to the Cb colourcomponent. ph_alf_chroma_idc equal to 2 indicates that the adaptive loopfilter is applied to the Cr colour component. ph_alf_chroma_idc equal to3 indicates that the adaptive loop filter is applied to Cb and Cr colourcomponents. When ph_alf_chroma_idc is not present, it is inferred to beequal to 0.

The semantics of SH syntax elements are changes as follows:

slice_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id ofthe i-th ALF APS that the luma component of the slice refers to.-Whenslice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_luma[i] is notpresent, the value of slice_alf_aps_id_luma[i] is inferred to be equalto the value of ph_alf_aps_id_luma[i].

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal toslice_alf_aps_id_luma[i] shall be less than or equal to the TemporalIdof the coded slice NAL unit. The value of alf_luma_filter_signal_flag ofthe APS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_alf_aps_id_luma[i] shall beequal to 1.

And the semantics of the APS syntax elements in the ALF data syntaxstructure are changed as follows:

alf_chroma_filter_signal_flag equal to 1 specifies that a chroma filteris signalled. alf_chroma_filter_signal_flag equal to 0 specifies that achroma filter is not signalled. [[When ChromaArrayType is equal to 0,alf_chroma_filter_signal_flag shall be equal to 0.]]

alf_cc_cb_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cb colour component are signalled.alf_cc_cb_filter_signal_flag equal to 0 specifies that cross-componentfilters for Cb colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cb_filter_signal_flag shall beequal to 0.]]

alf_cc_cr_ffiter_signal_flag equal to 1 specifies that cross-componentfilters for the Cr colour component are signalled.alf_cc_cr_filter_signal_flag equal to 0 specifies that cross-componentfilters for the Cr colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cr_filter_signal_flag shall beequal to 0.]]

6.1.7. An Embodiment for 1.c.iii

The semantics of PH syntax elements are changes as follows:

ph_alf_aps_id_chroma specifies the adaptation_parameter_set_id of theALF APS that the chroma component of the slices associated with the PHrefers to.

The value of alf_chroma_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto ph_alf_aps_id_chroma shall be equal to 1.

ph_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id of the ALFAPS that the Cb colour component of the slices associated with the PHrefers to

The value of alf_cc_cb_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto ph_cc_alf_cb_aps_id shall be equal to 1.

ph_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id of the ALFAPS that the Cr colour component of the slices associated with the PHrefers to.

The value of alf_cc_cr_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto ph_cc_alf_cr_aps_id shall be equal to 1.

The semantics of SH syntax elements are changes as follows:

slice_alf_aps_id_chroma specifies the adaptation_parameter_set_id of theALF APS that the chroma component of the slice refers to. The TemporalIdof the APS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_alf_aps_id_chroma shall beless than or equal to the TemporalId of the coded slice NAL unit. Whenslice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_chroma is notpresent, the value of slice_alf_aps_id_chroma is inferred to be equal tothe value of ph_alf_aps_id_chroma. The value ofalf_chroma_filter_signal_flag of the APS NAL unit having aps_params_typeequal to ALF_APS and adaptation_parameter_set_id equal toslice_alf_aps_id_chroma shall be equal to 1.

slice_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id thatthe Cb colour component of the slice refers to.

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal to slice_cc_alf_cb_aps_idshall be less than or equal to the TemporalId of the coded slice NALunit. When slice_cc_alf_cb_enabled_flag is equal to 1 andslice_cc_alf_cb_aps_id is not present, the value ofslice_cc_alf_cb_aps_id is inferred to be equal to the value ofph_cc_alf_cb_aps_id.

The value of alf_cc_cb_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto slice_cc_alf_cb_aps_id shall be equal to 1.

slice_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id thatthe Cr colour component of the slice refers to. The TemporalId of theAPS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_cc_alf_cr_aps_id shall beless than or equal to the TemporalId of the coded slice NAL unit. Whenslice_cc_alf_cr_enabled_flag is equal to 1 and slice_cc_alf_cr_aps_id isnot present, the value of slice_cc_alf_cr_aps_id is inferred to be equalto the value of ph_cc_alf_cr_aps_id.

The value of alf_cc_cr_filter_signal_flag of the APS NAL unit havingaps_params_type equal to ALF_APS and adaptation_parameter_set_id equalto slice_cc_alf_cr_aps_id shall be equal to 1.

And the semantics of APS syntax elements are changed as follows:

alf_chroma_filter_signal_flag equal to 1 specifies that a chroma filteris signalled. alf_chroma_filter_signal_flag equal to 0 specifies that achroma filter is not signalled. [[When ChromaArrayType is equal to 0,alf_chroma_filter_signal_flag shall be equal to 0.]]

alf_cc_cb_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cb colour component are signalled.alf_cc_cb_filter_signal_flag equal to 0 specifies that cross-componentfilters for Cb colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cb_filter_signal_flag shall beequal to 0.]]

alf_cc_cr_ffiter_signal_flag equal to 1 specifies that cross-componentfilters for the Cr colour component are signalled.alf_cc_cr_filter_signal_flag equal to 0 specifies that cross-componentfilters for the Cr colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cr_filter_signal_flag shall beequal to 0.]]

6.1.8. An Embodiment for 1.d.i

The semantics of APS syntax elements in the ALF data syntax structureare changed as follows:

alf_chroma_filter_signal_flag equal to 1 specifies that a chroma filteris signalled. alf_chroma_filter_signal_flag equal to 0 specifies that achroma filter is not signalled. [[When ChromaArrayType is equal to 0,alf_chroma_filter_signal_flag shall be equal to 0.]]

alf_cc_cb_filter_signal_flag equal to 1 specifies that cross-componentfilters for the Cb colour component are signalled.alf_cc_cb_filter_signal_flag equal to 0 specifies that cross-componentfilters for Cb colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cb_filter_signal_flag shall beequal to 0.]]

alf_cc_cr_ffiter_signal_flag equal to 1 specifies that cross-componentfilters for the Cr colour component are signalled.alf_cc_cr_filter_signal_flag equal to 0 specifies that cross-componentfilters for the Cr colour component are not signalled. [[WhenChromaArrayType is equal to 0, alf_cc_cr_filter_signal_flag shall beequal to 0.]]

6.1.9. An Embodiment for 1.d.ii

The semantics of APS syntax elements in the SCALING LIST data syntaxstructure are changed as follows:

scaling_list_chroma_present_flag equal to 1 specifies that chromascaling_lists are present in scaling_list_data( )scaling_list_chroma_present_flag equal to 0 specifies that chromascaling_lists are not present in scaling_list_data( ) [[It is arequirement of bitstream conformance thatscaling_list_chroma_present_flag shall be equal to 0 whenChromaArrayType is equal to 0, and shall be equal to 1 whenChromaArrayType is not equal to 0. . . ]]

6.1.10. An Embodiment for 1.e and 1.f

ph_scaling_list_aps_id specifies the adaptation_parameter_set_id of thescaling_list APS.

-   -   The TemporalId of the APS NAL unit having aps_params_type equal        to SCALING_APS and adaptation_parameter_set_id equal to        ph_scaling_list_aps_id shall be less than or equal to the        TemporalId of the picture associated with PH.

ph_lmcs_aps_id specifies the adaptation_parameter_set_id of the LMCS APSthat the slices associated with the PH refers to.

-   -   The TemporalId of the APS NAL unit having aps_params_type equal        to LMCS_APS and adaptation_parameter_set_id equal to        ph_lmcs_aps_id shall be less than or equal to the TemporalId of        the picture associated with PH.

ph_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of thei-th ALF APS that the luma component of the slices associated with thePH refers to.

-   -   The value of alf_luma_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to ph_alf_aps_id_luma[i] shall        be equal to 1.    -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        ph_alf_aps_id_luma[i] shall be less than or equal to the        TemporalId of the picture associated with the PH.

ph_alf_chroma_idc equal to 0 specifies that the adaptive loop filter isnot applied to Cb and Cr colour components. ph_alf_chroma_idc equal to 1indicates that the adaptive loop filter is applied to the Cb colourcomponent. ph_alf_chroma_idc equal to 2 indicates that the adaptive loopfilter is applied to the Cr colour component. ph_alf_chroma_idc equal to3 indicates that the adaptive loop filter is applied to Cb and Cr colourcomponents. When ph_alf_chroma_idc is not present, it is inferred to beequal to 0.

ph_alf_aps_id_chroma specifies the adaptation_parameter_set_id of theALF APS that the chroma component of the slices associated with the PHrefers to.

-   -   The value of alf_chroma_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to ph_alf_aps_id_chroma shall        be equal to 1.    -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        ph_alf_aps_id_chroma shall be less than or equal to the        TemporalId of the picture associated with the PH.

ph_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id of the ALFAPS that the Cb colour component of the slices associated with the PHrefers to.

-   -   The value of alf_cc_cb_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to ph_cc_alf_cb_aps_id shall        be equal to 1.    -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        ph_cc_alf_cb_aps_id shall be less than or equal to the        TemporalId of the picture associated with the PH.

ph_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id of the ALFAPS that the Cr colour component of the slices associated with the PHrefers to.

-   -   The value of alf_cc_cr_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to ph_cc_alf_cr_aps_id shall        be equal to 1.    -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        ph_cc_alf_cr_aps_id shall be less than or equal to the        TemporalId of the picture associated with the PH.

slice_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id ofthe i-th ALF APS that the luma component of the slice refers to.-Whenslice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_luma[i] is notpresent, the value of slice_alf_aps_id_luma[i] is inferred to be equalto the value of ph_alf_aps_id_luma[i].

-   -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        slice_alf_aps_id_luma[i] shall be less than or equal to the        TemporalId of the coded slice NAL unit.    -   The value of alf_luma_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to slice_alf_aps_id_luma[i]        shall be equal to 1.

slice_alf_aps_id_chroma specifies the adaptation_parameter_set_id of theALF APS that the chroma component of the slice refers to. Whenslice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_chroma is notpresent, the value of slice_alf_aps_id_chroma is inferred to be equal tothe value of ph_alf_aps_id_chroma.

-   -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        slice_alf_aps_id_chroma shall be less than or equal to the        TemporalId of the coded slice NAL unit.    -   The value of alf_chroma_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to slice_alf_aps_id_chroma        shall be equal to 1.

slice_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id thatthe Cb colour component of the slice refers to.

When slice_cc_alf_cb_enabled_flag is equal to 1 andslice_cc_alf_cb_aps_id is not present, the value ofslice_cc_alf_cb_aps_id is inferred to be equal to the value ofph_cc_alf_cb_aps_id.

-   -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        slice_cc_alf_cb_aps_id shall be less than or equal to the        TemporalId of the coded slice NAL unit.    -   The value of alf_cc_cb_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to slice_cc_alf_cb_aps_id        shall be equal to 1.

slice_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id thatthe Cr colour component of the slice refers to. Whenslice_cc_alf_cr_enabled_flag is equal to 1 and slice_cc_alf_cr_aps_id isnot present, the value of slice_cc_alf_cr_aps_id is inferred to be equalto the value of ph_cc_alf_cr_aps_id.

-   -   The TemporalId of the APS NAL unit having aps_params_type equal        to ALF_APS and adaptation_parameter_set_id equal to        slice_cc_alf_cr_aps_id shall be less than or equal to the        TemporalId of the coded slice NAL unit.    -   The value of alf_cc_cr_filter_signal_flag of the APS NAL unit        having aps_params_type equal to ALF_APS and        adaptation_parameter_set_id equal to slice_cc_alf_cr_aps_id        shall be equal to 1.

6.1.11. An Embodiment for 1.g

The semantics of SH syntax elements are changes as follows:

slice_alf_aps_id_chroma specifies the adaptation_parameter_set_id of theALF APS that the chroma component of the slice refers to. The TemporalIdof the APS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_alf_aps_id_chroma shall beless than or equal to the TemporalId of the coded slice NAL unit. Whenslice_alf_enabled_flag is equal to 1 and slice_alf_aps_id_chroma is notpresent

the value of slice_alf_aps_id_chroma is inferred to be equal to thevalue of ph_alf_aps_id_chroma.

slice_cc_alf_cb_aps_id specifies the adaptation_parameter_set_id thatthe Cb colour component of the slice refers to.

The TemporalId of the APS NAL unit having aps_params_type equal toALF_APS and adaptation_parameter_set_id equal to slice_cc_alf_cb_aps_idshall be less than or equal to the TemporalId of the coded slice NALunit. When slice_cc_alf_cb_enabled_flag is equal to 1 andslice_cc_alf_cb_aps_id is not present

the value of slice_cc_alf_cb_aps_id is inferred to be equal to the valueof ph_cc_alf_cb_aps_id.

slice_cc_alf_cr_aps_id specifies the adaptation_parameter_set_id thatthe Cr colour component of the slice refers to. The TemporalId of theAPS NAL unit having aps_params_type equal to ALF_APS andadaptation_parameter_set_id equal to slice_cc_alf_cr_aps_id shall beless than or equal to the TemporalId of the coded slice NAL unit. Whenslice_cc_alf_cr_enabled_flag is equal to 1 and slice_cc_alf_cr_aps_id isnot present

the value of slice_cc_alf_cr_aps_id is inferred to be equal to the valueof ph_cc_alf_cr_aps_id.

6.2. Second Set of Embodiments

This is a set of embodiments for items 2 (from 2.a to 2.c) summarizedabove in Section 5.

The syntax structure pic_parameter_set_rbsp( )is changed as follows:

Descriptor pic_parameter_set_rbsp( ) {  pps _(—) pic _(—) parameter _(—)set _(—) id ue(v) ...  deblocking _(—) filter _(—) [[control _(—)present _(—) flag]] 

u([[1]] 

 )  if( deblocking_filter_[[control_present_flag]] 

 ) {   [[deblocking _(—) filter _(—) override _(—) enabled _(—) flag]]u([[1]]   [[deblocking _(—) filter _(—) disabled _(—) flag]] u([[1]]  [[if( !pps_deblocking_filter_disabled_flag ) { }]    pps _(—) beta_(—) offset _(—) div2 se(v)    pps _(—) tc _(—) offset _(—) div2 se(v)   pps _(—) cb _(—) beta _(—) offset _(—) div2 se(v)    pps _(—) cb _(—)tc _(—) offset _(—) div2 se(v)    pps _(—) cr _(—) beta _(—) offset _(—)div2 se(v)    pps _(—) cr _(—) tc _(—) offset _(—) div2 se(v)   [[}]]  } [[rpl _(—) info _(—) in _(—) ph _(—) flag]] u([[1]]  if(deblocking_filter_[[override_enabled_flag]] 

 )   

 

...

. . .

[[deblocking_filter_control_present_flag equal to 1 specifies thepresence of deblocking filter control syntax elements in the PPS.deblocking_filter_control_present_flag equal to 0 specifies the absenceof deblocking filter control syntax elements in the PPS.

deblocking_filter_override_enabled_flag equal to 1 specifies thepresence of ph_deblocking_filter_override_flag in the PHs referring tothe PPS or slice_deblocking_filter_override_flag in the slice headersreferring to the PPS. deblocking_filter_override_enabled_flag equal to 0specifies the absence of ph_deblocking_filter_override_flag in PHsreferring to the PPS or slice_deblocking_filter_override_flag in sliceheaders referring to the PPS. When not present, the value ofdeblocking_filter_override_enabled_flag is inferred to be equal to 0.

pps_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of deblocking filter is not applied for slices referring tothe PPS in which slice_deblocking_filter_disabled_flag is not present.pps_deblocking_filter_disabled_flag equal to 0 specifies that theoperation of the deblocking filter is applied for slices referring tothe PPS in which slice_deblocking_filter_disabled_flag is not present.When not present, the value of pps_deblocking_filter_disabled_flag isinferred to be equal to 0.]]

dbf_info_in_ph_flag equal to 1 specifies that deblocking_filterinformation is present in the PH syntax structure and not present inslice headers referring to the PPS that do not contain a PH syntaxstructure. dbf_info_in_ph_flag equal to 0 specifies thatdeblocking_filter information is not present in the PH syntax structureand may be present in slice headers referring to the PPS that do notcontain a PH syntax structure. [[When not present, the value ofdbf_info_in_ph_flag is inferred to be equal to 0.]]

And the syntax structure picture_header_structure( )is changed asfollows:

Descriptor picture_header_structure( ) {  gdr _(—) or _(—) irap _(—) pic_(—) flag u(1) ...   if( deblocking_filter_[[override_enabled_flag]] 

dbf_info_in_ph_flag) {    ph _(—) deblocking _(—) filter _(—)[[override]] 

u(1)    if( ph_deblocking_filter_[[override]] 

 _flag ) { u(1)  ph _(—) deblocking _(—) [[filter _(—) disabled]] 

    if( [[!]]ph_deblocking_[[filter_disabled]] 

 _flag ) }      ph _(—) beta _(—) offset _(—) div2 se(v)      ph _(—) tc_(—) offset _(—) div2 se(v)      ph _(—) cb _(—) beta _(—) offset _(—)div2 se(v)      ph _(—) cb _(—) tc _(—) offset _(—) div2 se(v)      ph_(—) cr _(—) beta _(—) offset _(—) div2 se(v)      ph _(—) cr _(—) tc_(—) offset _(—) div2 se(v)    }   }  } ...

ph_deblocking_filter used flag equal to 1 specifies that the deblockingfilter is applied for the slices in the current picture.ph_deblockingJilter used flag equal to 0 specifies that the deblockingfilter is not applied for the slices in the current picture. When notpresent, the value of ph_deblockingJilter used flag is inferred to beequal to (deblocking _filter_mode_idc >0).

ph_deblocking_[[filter]]

_override_flag equal to 1 specifies that deblocking parameters arepresent in the PH. ph_deblocking_[[filter]]

_override_flag equal to 0 specifies that deblocking parameters are notpresent in the PH. When not present, the value ofph_deblocking_filter_override_flag is inferred to be equal to 0.

[[ph_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of the deblocking filter is not applied for the slicesassociated with the PH. ph_deblocking_filter_disabled_flag equal to 0specifies that the operation of the deblocking filter is applied for theslices associated with the PH. When ph_deblocking_filter_disabled_flagis not present, it is inferred to be equal topps_deblocking_filter_disabled_flag]]

And the syntax structure slice_header ( )is changed as follows:

Descriptor slice_header( ) {  picture _(—) header _(—) in _(—) slice_(—) header _(—) flag u(1) ...   if(deblocking_filter_[[override_enabled_flag]] 

!dbf_info_in_ph_flag )    slice _(—) deblocking _(—) filter _(—)[[override]] 

 flag u(1)   if( slice_deblocking_filter_[[override]] 

 _flag ) {    slice _(—) deblocking _(—) [[filter _(—) disabled]] 

 _(—) flag u(1)    if( [[!]]slice_deblocking_[[filter_disabled]] 

 _flag ) {     slice _(—) beta _(—) offset _(—) div2 se(v)     slice_(—) tc _(—) offset _(—) div2 se(v)     slice _(—) cb _(—) beta _(—)offset _(—) div2 se(v)     slice _(—) cb _(—) tc _(—) offset _(—) div2se(v)     slice _(—) cr _(—) beta _(—) offset _(—) div2 se(v)     slice_(—) cr _(—) tc _(—) offset _(—) div2 se(v)    }   } ...

slice_deblocking_[[filter]]

_override _flag equal to 1 specifies that deblocking parameters arepresent in the slice header. slice_deblocking_[[filter]]

_override_flag equal to 0 specifies that deblocking parameters are notpresent in the slice header, When not present, the value ofslice_deblocking_filter_override_flag is inferred to be equal to[[ph_deblocking_filter_override_flag]]

.

[[slice_deblocking_filter_disabled_flag equal to 1 specifies that theoperation of the deblocking filter is not applied for the current slice.slice_deblocking_filter_disabled_flag equal to 0 specifies that theoperation of the deblocking filter is applied for the current slice.When slice_deblocking_filter_disabled_flag is not present, it isinferred to be equal to ph_deblocking_filter_disabled_flag.]]

And the decoding process of deblocking_filter process is changed asfollows:

8.8.3 Deblocking Filter Process 8.8.3.1 General

The deblocking_filter process is applied to all coding subblock edgesand transform block edges of a picture, except the following types ofedges:

-   -   Edges that are at the boundary of the picture,    -   Edges that coincide with the boundaries of a subpicture with        subpicture index subpicIdx and        loop_filter_across_subpic_enabled_flag[subpicIdx] is equal to 0,    -   Edges that coincide with the virtual boundaries of the picture        when VirtualBoundariesPresentFlag is equal to 1,    -   Edges that coincide with tile boundaries when        loop_filter_across_tiles_enabled_flag is equal to 0,    -   Edges that coincide with slice boundaries when        loop_filter_across_slices_enabled_flag is equal to 0,    -   Edges that coincide with upper or left boundaries of slices with        slice_deblocking_filter_        [[disabled]]_flag equal to [[1]]        ,    -   Edges within slices with slice_deblocking_filter_        [[disabled]]_flag equal to [[1]]        ,    -   Edges that do not correspond to 4×4 sample grid boundaries of        the luma component,    -   Edges that do not correspond to 8×8 sample grid boundaries of        the chroma component,    -   Edges within the luma component for which both sides of the edge        have intra_bdpcm_luma_flag equal to 1,    -   Edges within the chroma components for which both sides of the        edge have intra_bdpcm_chroma_flag equal to 1,    -   Edges of chroma subblocks that are not edges of the associated        transform unit.

The edge type, vertical or horizontal, is represented by the variableedgeType as specified in Table 42.

TABLE 42 Name of association to edgeType edgeType Name of edgeType 0(vertical edge) EDGE_VER 1 (horizontal edge) EDGE_HOR

When slice_deblocking_filter_

[[disabled]]_flag of the current slice is equal to [[0]]

, the following applies:

-   -   The variable treeType is set equal to DUAL_TREE_LUMA.    -   The vertical edges are filtered by invoking the deblocking        filter process for one direction as specified in clause 8.8.3.2        with the variable treeType, the reconstructed picture prior to        deblocking, i.e., the array recPicture_(L) and the variable        edgeType set equal to EDGE_VER as inputs, and the modified        reconstructed picture after deblocking, i.e., the array        recPicture_(L) as outputs.    -   The horizontal edge are filtered by invoking the deblocking        filter process for one direction as specified in clause 8.8.3.2        with the variable treeType, the modified reconstructed picture        after deblocking, i.e., the array recPicture_(L) and the        variable edgeType set equal to EDGE_HOR as inputs, and the        modified reconstructed picture after deblocking, i.e., the array        recPicture_(L) as outputs.    -   When ChromaArrayType is not equal to 0, the following applies:        -   The variable treeType is set equal to DUAL_TREE_CHROMA        -   The vertical edges are filtered by invoking the deblocking            filter process for one direction as specified in clause            8.8.3.2 with the variable treeType, the reconstructed            picture prior to deblocking, i.e., the arrays            recPicture_(Cb) and recPicture_(Cr), and the variable            edgeType set equal to EDGE_VER as inputs, and the modified            reconstructed picture after deblocking, i.e., the arrays            recPicture_(Cb) and recPicture_(Cr) as outputs.        -   The horizontal edge are filtered by invoking the            deblocking_filter process for one direction as specified in            clause 8.8.3.2 with the variable treeType, the modified            reconstructed picture after deblocking, i.e., the arrays            recPicture_(Cb) and recPicture_(Cr), and the variable            edgeType set equal to EDGE_HOR as inputs, and the modified            reconstructed picture after deblocking, i.e., the arrays            recPicture_(Cb) and recPicture_(Cr) as outputs.

6.3. Third Set of Embodiments

The changes, marked in boldfaced italics, are based on JVET-Q2001-vE.

The i-th chroma QP mapping table ChromaQpTable[i] for i=0..numQpTables−1 is derived as follows:

qpInVal[ i ][ 0 ] = qp_table_start_minus26[ i ] + 26 qpOutVal[ i ][ 0 ]= qpInVal[ i ][ 0 ] for( j = 0; j <= num_points_in_qp_table_minus1[ i ];j++ ) {  qpInVal[ i ][ j + 1 ] = qpInVal[ i ][ j ] +delta_qp_in_val_minus1[  i ][ j ] + 1  qpOutVal[ i ][ j + 1 ] =qpOutVal[ i ][ j ] +  ( 

 delta_qp_in_val_minus1[ i ][ j ] + 

  {circumflex over ( )} delta_qp_diff_val[ i ][ j ] ) } ChromaQpTable[ i][ qpInVal[ i ][ 0 ] ] = qpOutVal[ i ][ 0 ] for( k = qpInVal[ i ][ 0 ] −1; k >= −QpBdOffset; k − − )  ChromaQpTable[ i ][ k ] = Clip3(−QpBdOffset, 63,  ChromaQpTable[ i ][ k + 1 ] − 1 ) for( j = 0; j <=num_points_in_qp_table_minus1[ i ]; j++ ) {  sh = (delta_qp_in_val_minus1[ i ][j ] + 1 ) >> 1  for( k = qpInVal[ i ][ j ] +1, m = 1; k <= qpInval[ i ][ j + 1 ]; k++,  m++ )   ChromaQpTable[ i ][k ] = ChromaQpTable[ i ][ qpInVal[ i ][ j ] ] +    ( ( qpOutVal[ i ][j +1] − qpOutVal[ i ][j ] ) * m + sh ) / ( delta_qp_in_val_minus1[ i ][j] +1 ) } for( k = qpInVal[ i ][ num_points_in_qp_table_minus1[ i ] + 1 ] +1; k <= 63; k++ )  ChromaQpTable[ i ][ k ] = Clip3( −QpBdOffset, 63, ChromaQpTable[ i ][ k − 1 ] + 1 )

When same_qp_table_for_chroma is equal to 1, ChromaQpTable[1][k] andChromaQpTable[2][k] are set equal to ChromaQpTable[0][k] for k in therange of −QpBdOffset to 63, inclusive.

-   -   It is a requirement of bitstream conformance that the values of        qpInVal[i][j] and qpOutVal[i][j] shall be in the range of        −QpBdOffset to 63, inclusive for i in the range of 0 to        numQpTables −1, inclusive, and j in the range of 0 to        num_points_in_qp_table_minus1[i]+1, inclusive.

FIG. 1 is a block diagram showing an example video processing system1900 in which various techniques disclosed herein may be implemented.Various implementations may include some or all of the components of thesystem 1900. The system 1900 may include input 1902 for receiving videocontent. The video content may be received in a raw or uncompressedformat, e.g., 8 or 10 bit multi-component pixel values, or may be in acompressed or encoded format. The input 1902 may represent a networkinterface, a peripheral bus interface, or a storage interface. Examplesof network interface include wired interfaces such as Ethernet, passiveoptical network (PON), etc. and wireless interfaces such as wirelessfidelity (Wi-Fi) or cellular interfaces.

The system 1900 may include a coding component 1904 that may implementthe various coding or encoding methods described in the presentdocument. The coding component 1904 may reduce the average bitrate ofvideo from the input 1902 to the output of the coding component 1904 toproduce a coded representation of the video. The coding techniques aretherefore sometimes called video compression or video transcodingtechniques. The output of the coding component 1904 may be eitherstored, or transmitted via a communication connected, as represented bythe component 1906. The stored or communicated bitstream (or coded)representation of the video received at the input 1902 may be used bythe component 1908 for generating pixel values or displayable video thatis sent to a display interface 1910. The process of generatinguser-viewable video from the bitstream representation is sometimescalled video decompression. Furthermore, while certain video processingoperations are referred to as “coding” operations or tools, it will beappreciated that the coding tools or operations are used at an encoderand corresponding decoding tools or operations that reverse the resultsof the coding will be performed by a decoder.

Examples of a peripheral bus interface or a display interface mayinclude universal serial bus (USB) or high definition multimediainterface (HDMI) or Displayport, and so on. Examples of storageinterfaces include serial advanced technology attachment (SATA),peripheral component interconnect (PCI), integrated drive electronics(IDE) interface, and the like. The techniques described in the presentdocument may be embodied in various electronic devices such as mobilephones, laptops, smartphones or other devices that are capable ofperforming digital data processing and/or video display.

FIG. 2 is a block diagram of a video processing apparatus 3600. Theapparatus 3600 may be used to implement one or more of the methodsdescribed herein. The apparatus 3600 may be embodied in a smartphone,tablet, computer, Internet of Things (IoT) receiver, and so on. Theapparatus 3600 may include one or more processors 3602, one or morememories 3604 and video processing hardware 3606. The processor(s) 3602may be configured to implement one or more methods described in thepresent document. The memory (memories) 3604 may be used for storingdata and code used for implementing the methods and techniques describedherein. The video processing hardware 3606 may be used to implement, inhardware circuitry, some techniques described in the present document.

FIG. 4 is a block diagram that illustrates an example video codingsystem 100 that may utilize the techniques of this disclosure.

As shown in FIG. 4 , video coding system 100 may include a source device110 and a destination device 120. Source device 110 generates encodedvideo data which may be referred to as a video encoding device.Destination device 120 may decode the encoded video data generated bysource device 110 which may be referred to as a video decoding device.

Source device 110 may include a video source 112, a video encoder 114,and an input/output (I/O) interface 116.

Video source 112 may include a source such as a video capture device, aninterface to receive video data from a video content provider, and/or acomputer graphics system for generating video data, or a combination ofsuch sources. The video data may comprise one or more pictures. Videoencoder 114 encodes the video data from video source 112 to generate abitstream. The bitstream may include a sequence of bits that form acoded representation of the video data. The bitstream may include codedpictures and associated data. The coded picture is a codedrepresentation of a picture. The associated data may include sequenceparameter sets, picture parameter sets, and other syntax structures. I/Ointerface 116 may include a modulator/demodulator (modem) and/or atransmitter. The encoded video data may be transmitted directly todestination device 120 via I/O interface 116 through network 130a. Theencoded video data may also be stored onto a storage medium/server 130bfor access by destination device 120.

Destination device 120 may include an I/O interface 126, a video decoder124, and a display device 122.

I/O interface 126 may include a receiver and/or a modem. I/O interface126 may acquire encoded video data from the source device 110 or thestorage medium/ server 130b. Video decoder 124 may decode the encodedvideo data. Display device 122 may display the decoded video data to auser. Display device 122 may be integrated with the destination device120, or may be external to destination device 120 which be configured tointerface with an external display device.

Video encoder 114 and video decoder 124 may operate according to a videocompression standard, such as the High Efficiency Video Coding (HEVC)standard, Versatile Video Coding (VVC) standard and other current and/orfurther standards.

FIG. 5 is a block diagram illustrating an example of video encoder 200,which may be video encoder 114 in the system 100 illustrated in FIG. 4 .

Video encoder 200 may be configured to perform any or all of thetechniques of this disclosure. In the example of FIG. 5 , video encoder200 includes a plurality of functional components. The techniquesdescribed in this disclosure may be shared among the various componentsof video encoder 200. In some examples, a processor may be configured toperform any or all of the techniques described in this disclosure.

The functional components of video encoder 200 may include a partitionunit 201, a prediction unit 202 which may include a mode select unit203, a motion estimation unit 204, a motion compensation unit 205 and anintra prediction unit 206, a residual generation unit 207, a transformunit 208, a quantization unit 209, an inverse quantization unit 210, aninverse transform unit 211, a reconstruction unit 212, a buffer 213, andan entropy encoding unit 214.

In other examples, video encoder 200 may include more, fewer, ordifferent functional components. In an example, prediction unit 202 mayinclude an intra block copy (IBC) unit. The IBC unit may performprediction in an IBC mode in which at least one reference picture is apicture where the current video block is located.

Furthermore, some components, such as motion estimation unit 204 andmotion compensation unit 205 may be highly integrated, but arerepresented in the example of FIG. 5 separately for purposes ofexplanation.

Partition unit 201 may partition a picture into one or more videoblocks. Video encoder 200 and video decoder 300 may support variousvideo block sizes.

Mode select unit 203 may select one of the coding modes, intra or inter,e.g., based on error results, and provide the resulting intra- orinter-coded block to a residual generation unit 207 to generate residualblock data and to a reconstruction unit 212 to reconstruct the encodedblock for use as a reference picture. In some example, Mode select unit203 may select a combination of intra and inter prediction (CIIP) modein which the prediction is based on an inter prediction signal and anintra prediction signal. Mode select unit 203 may also select aresolution for a motion vector (e.g., a sub-pixel or integer pixelprecision) for the block in the case of inter-prediction.

To perform inter prediction on a current video block, motion estimationunit 204 may generate motion information for the current video block bycomparing one or more reference frames from buffer 213 to the currentvideo block. Motion compensation unit 205 may determine a predictedvideo block for the current video block based on the motion informationand decoded samples of pictures from buffer 213 other than the pictureassociated with the current video block.

Motion estimation unit 204 and motion compensation unit 205 may performdifferent operations for a current video block, for example, dependingon whether the current video block is in an I slice, a P slice, or a Bslice.

In some examples, motion estimation unit 204 may perform uni-directionalprediction for the current video block, and motion estimation unit 204may search reference pictures of list 0 or list 1 for a reference videoblock for the current video block. Motion estimation unit 204 may thengenerate a reference index that indicates the reference picture in list0 or list 1 that contains the reference video block and a motion vectorthat indicates a spatial displacement between the current video blockand the reference video block. Motion estimation unit 204 may output thereference index, a prediction direction indicator, and the motion vectoras the motion information of the current video block. Motioncompensation unit 205 may generate the predicted video block of thecurrent block based on the reference video block indicated by the motioninformation of the current video block.

In other examples, motion estimation unit 204 may perform bi-directionalprediction for the current video block, motion estimation unit 204 maysearch the reference pictures in list 0 for a reference video block forthe current video block and may also search the reference pictures inlist 1 for another reference video block for the current video block.Motion estimation unit 204 may then generate reference indexes thatindicate the reference pictures in list 0 and list 1 containing thereference video blocks and motion vectors that indicate spatialdisplacements between the reference video blocks and the current videoblock. Motion estimation unit 204 may output the reference indexes andthe motion vectors of the current video block as the motion informationof the current video block. Motion compensation unit 205 may generatethe predicted video block of the current video block based on thereference video blocks indicated by the motion information of thecurrent video block.

In some examples, motion estimation unit 204 may output a full set ofmotion information for decoding processing of a decoder.

In some examples, motion estimation unit 204 may not output a full setof motion information for the current video. Rather, motion estimationunit 204 may signal the motion information of the current video blockwith reference to the motion information of another video block. Forexample, motion estimation unit 204 may determine that the motioninformation of the current video block is sufficiently similar to themotion information of a neighboring video block.

In one example, motion estimation unit 204 may indicate, in a syntaxstructure associated with the current video block, a value thatindicates to the video decoder 300 that the current video block has thesame motion information as another video block.

In another example, motion estimation unit 204 may identify, in a syntaxstructure associated with the current video block, another video blockand a motion vector difference (MVD). The motion vector differenceindicates a difference between the motion vector of the current videoblock and the motion vector of the indicated video block. The videodecoder 300 may use the motion vector of the indicated video block andthe motion vector difference to determine the motion vector of thecurrent video block.

As discussed above, video encoder 200 may predictively signal the motionvector. Two examples of predictive signaling techniques that may beimplemented by video encoder 200 include advanced motion vectorprediction (AMVP) and merge mode signaling.

Intra prediction unit 206 may perform intra prediction on the currentvideo block. When intra prediction unit 206 performs intra prediction onthe current video block, intra prediction unit 206 may generateprediction data for the current video block based on decoded samples ofother video blocks in the same picture. The prediction data for thecurrent video block may include a predicted video block and varioussyntax elements.

Residual generation unit 207 may generate residual data for the currentvideo block by subtracting (e.g., indicated by the minus sign) thepredicted video block(s) of the current video block from the currentvideo block. The residual data of the current video block may includeresidual video blocks that correspond to different sample components ofthe samples in the current video block.

In other examples, there may be no residual data for the current videoblock for the current video block, for example in a skip mode, andresidual generation unit 207 may not perform the subtracting operation.

Transform processing unit 208 may generate one or more transformcoefficient video blocks for the current video block by applying one ormore transforms to a residual video block associated with the currentvideo block.

After transform processing unit 208 generates a transform coefficientvideo block associated with the current video block, quantization unit209 may quantize the transform coefficient video block associated withthe current video block based on one or more quantization parameter (QP)values associated with the current video block.

Inverse quantization unit 210 and inverse transform unit 211 may applyinverse quantization and inverse transforms to the transform coefficientvideo block, respectively, to reconstruct a residual video block fromthe transform coefficient video block. Reconstruction unit 212 may addthe reconstructed residual video block to corresponding samples from oneor more predicted video blocks generated by the prediction unit 202 toproduce a reconstructed video block associated with the current blockfor storage in the buffer 213.

After reconstruction unit 212 reconstructs the video block, loopfiltering operation may be performed reduce video blocking artifacts inthe video block.

Entropy encoding unit 214 may receive data from other functionalcomponents of the video encoder 200. When entropy encoding unit 214receives the data, entropy encoding unit 214 may perform one or moreentropy encoding operations to generate entropy encoded data and outputa bitstream that includes the entropy encoded data.

FIG. 6 is a block diagram illustrating an example of video decoder 300which may be video decoder 124 in the system 100 illustrated in FIG. 4 .

The video decoder 300 may be configured to perform any or all of thetechniques of this disclosure. In the example of FIG. 6 , the videodecoder 300 includes a plurality of functional components. Thetechniques described in this disclosure may be shared among the variouscomponents of the video decoder 300. In some examples, a processor maybe configured to perform any or all of the techniques described in thisdisclosure.

In the example of FIG. 6 , video decoder 300 includes an entropydecoding unit 301, a motion compensation unit 302, an intra predictionunit 303, an inverse quantization unit 304, an inverse transformationunit 305, and a reconstruction unit 306 and a buffer 307. Video decoder300 may, in some examples, perform a decoding pass generally reciprocalto the encoding pass described with respect to video encoder 200 (FIG. 5).

Entropy decoding unit 301 may retrieve an encoded bitstream. The encodedbitstream may include entropy coded video data (e.g., encoded blocks ofvideo data). Entropy decoding unit 301 may decode the entropy codedvideo data, and from the entropy decoded video data, motion compensationunit 302 may determine motion information including motion vectors,motion vector precision, reference picture list indexes, and othermotion information. Motion compensation unit 302 may, for example,determine such information by performing the AMVP and merge mode.

Motion compensation unit 302 may produce motion compensated blocks,possibly performing interpolation based on interpolation filters.Identifiers for interpolation filters to be used with sub-pixelprecision may be included in the syntax elements.

Motion compensation unit 302 may use interpolation filters as used byvideo encoder 200 during encoding of the video block to calculateinterpolated values for sub-integer pixels of a reference block. Motioncompensation unit 302 may determine the interpolation filters used byvideo encoder 200 according to received syntax information and use theinterpolation filters to produce predictive blocks.

Motion compensation unit 302 may use some of the syntax information todetermine sizes of blocks used to encode frame(s) and/or slice(s) of theencoded video sequence, partition information that describes how eachmacroblock of a picture of the encoded video sequence is partitioned,modes indicating how each partition is encoded, one or more referenceframes (and reference frame lists) for each inter-encoded block, andother information to decode the encoded video sequence.

Intra prediction unit 303 may use intra prediction modes for examplereceived in the bitstream to form a prediction block from spatiallyadjacent blocks. Inverse quantization unit 303 inverse quantizes, i.e.,de-quantizes, the quantized video block coefficients provided in thebitstream and decoded by entropy decoding unit 301. Inverse transformunit 303 applies an inverse transform.

Reconstruction unit 306 may sum the residual blocks with thecorresponding prediction blocks generated by motion compensation unit302 or intra-prediction unit 303 to form decoded blocks. If desired, adeblocking_filter may also be applied to filter the decoded blocks inorder to remove blockiness artifacts. The decoded video blocks are thenstored in buffer 307, which provides reference blocks for subsequentmotion compensation/intra prediction and also produces decoded video forpresentation on a display device.

A listing of examples preferred by some embodiments is provided next.

The first set of clauses show example embodiments of techniquesdiscussed in the previous section. The following clauses show exampleembodiments of techniques discussed in the previous section (e.g., item1).

1. A video processing method (e.g., method 3000 s hown in FIG. 3 ),comprising: performing (3002) a conversion between a video having one ormore chroma components, the video comprising one or more video picturescomprising one or more slices and a coded representation of the video,wherein the coded representation conforms to a format rule, wherein theformat rule specifies that a chroma array type field controls aconstraint on a conversion characteristic of chroma used during theconversion.

2. The method of clause 1, wherein the conversion characteristicincludes a constraint on a field indicative of presence of one or morescaling_lists for the one or more chroma components.

3. The method of clause 1, wherein the conversion characteristicincludes a constraint on a value of a field indicative of a codewordused for signaling luma mapping with chroma scaling.

4. The method of clause 1, wherein the conversion characteristicincludes a constraint on values of syntax elements describing anadaptation parameter set for an adaptive loop filter used during theconversion.

5. The method of clause 1, wherein the format rule specifies to use asame semantics of one or more entries of an adaptation parameter set forthe chroma array type field signaling a 4:0:0 format or a separate colorcoding format.

6. The method of clause 5, wherein the one or more entries include anadaptive loop filter parameter or a scaling_list parameter or a lumamapping with chroma scaling parameter.

7. The method of clauses 5-6, wherein the format rule further specifiesthat a constraint on the one or more entries of the adaptation parameterset is dependent on whether an identifier of the adaptation parameterset is included in the bitstream.

The following clauses show example embodiments of techniques discussedin the previous section (e.g., item 2).

8. A video processing method, comprising: performing a conversionbetween a video comprising one or more video pictures comprising one ormore video regions and a coded representation of the video, wherein thecoded representation conforms to a format rule that specifies theinclude a deblocking mode indicator for a video region indicative ofapplicability of a deblocking_filter to the video region during theconversion.

9. The method of clause 8, wherein the deblocking mode indicator is an Nbit field where N is an integer greater than 1.

10. The method of any of clauses 8-9, wherein the deblocking modeindicator for the video region is included in a picture parameter set.

11. The method of clause 8, wherein the deblocking mode indicatorcorresponds to a flag included in a header of the video regionindicating applicability of the deblocking_filter to the video region.

12. The method of any of clauses 8-11, wherein the format rule specifiesthat a flag that signals whether deblocking_filter parameters signaledin the deblocking mode indicator are to override default parameters.

13. The method of any of clauses 8-12, wherein the video regioncorresponds to a video picture or a video slice.

The following clauses show example embodiments of techniques discussedin the previous section (e.g., item 3).

14. A video processing method, comprising: performing a conversionbetween a video comprising one or more video pictures comprising one ormore video slices and/or one or more video subpictures and a codedrepresentation of the video, wherein the coded representation conformsto a format rule that specifies that a flag indicating whether asingle_slice per subpicture mode is deemed to be enabled for a videopicture in case that a picture partitioning is disabled for the videopicture.

The following clauses show example embodiments of techniques discussedin the previous section (e.g., item 4).

15. A video processing method, comprising: performing a conversionbetween a video comprising one or more video pictures comprising one ormore video slices and a coded representation of the video, wherein thecoded representation conforms to a format rule that specifies that apicture or a slice level chroma quantization parameter offset issignaled in a picture header or a slice header.

16. The method of clause 15, wherein the format rule specifies toinclude slice level chroma quantization parameter offsets in the sliceheader.

The following clauses show example embodiments of techniques discussedin the previous section (e.g., item 5).

17. A video processing method, comprising: performing a conversionbetween a video comprising one or more video pictures comprising one ormore video slices and a coded representation of the video, wherein thecoded representation conforms to a format rule that specifies that achroma quantization parameter (QP) table applicable for conversion of avideo block of the video is derived as an XOR operation between(delta_qp_in_val_minus1[i][j]+1) and delta_qp_ diff_val[i][j], whereindelta_qp_in_val_minus1[i][j] specifies a delta value used to derive theinput coordinate of the j-th pivot point of the i-th chroma mappingtable and delta_qp_ diff_val[i][j] specifies a delta value used toderive the output coordinate of the j-th pivot point of the i-th chromaQP mapping table, where i and j are integers.

18. The method of any of clauses 1 to 17, wherein the conversioncomprises encoding the video into the coded representation.

19. The method of any of clauses 1 to 17, wherein the conversioncomprises decoding the coded representation to generate pixel values ofthe video.

20. A video decoding apparatus comprising a processor configured toimplement a method recited in one or more of clauses 1 to 19.

21. A video encoding apparatus comprising a processor configured toimplement a method recited in one or more of clauses 1 to 19.

22. A computer program product having computer code stored thereon, thecode, when executed by a processor, causes the processor to implement amethod recited in any of clauses 1 to 19.

23. A method, apparatus or system described in the present document.

A second set of clauses show example embodiments of techniques discussedin the previous section (e.g., items 2, 4, 5 and 6).

1. A method of video processing (e.g., method 700 as shown in FIG. 7A),comprising: performing 702 a conversion between a video comprising apicture and a bitstream of the video according to a format rule, andwherein the format rule specifies that a presence of a syntax element ina sequence parameter set that indicates a constrain on loop filteringacross subpicture boundaries is based on whether a number of subpicturesin the picture is greater than 1.

2. The method of clause 1, wherein the syntax element equal to a certainvalue specifies that all subpicture boundaries in a coded layer videosequence are treated as picture boundaries and there is no loopfiltering across the subpicture boundaries.

3. The method of clause 1 or 2, wherein the syntax element issps_independent_subpics_flag.

4. The method of clause any of 1 to 3, wherein the syntax element ispresent only in case that the number of subpictures in the picture isgreater than 1.

5. The method of clause any of clause 1 to 4, wherein the syntax elementis not present in case that the number of subpictures in the picture isequal to 1.

6. The method of clause 2, wherein the format rule specifies that, incase that the syntax element is not present, a value of the syntaxelement is inferred to be equal to the certain value.

7. The method of clause 2 or 6, wherein the certain value is equal to 1.

8. The method of clause 1, wherein the format rule specifies that, incase that the syntax element is not present, a value of the syntaxelement is inferred based on another syntax element.

9. The method of clause 5, wherein another syntax element corresponds toa subpicture information present flag indicating whether subpictureinformation is present or not.

10. The method of clause 5, wherein the value of the syntax element isinferred based on a value of a subpicture information present flagindicating whether subpicture information is present or not.

11. A method of video processing (e.g., method 710 as shown in FIG. 7B),comprising: performing 712 a conversion between a video comprising oneor more pictures and a bitstream of the video according to a formatrule, and wherein the format rule specifies how to infer a value of asyntax element that is not present, wherein the syntax element relatedto treating a subpicture as a picture for excluding in-loop filteringoperations.

12. The method of clause 11, wherein the syntax element indicateswhether to treat an i-th subpicture of each picture in a coded layervideo sequence is treated as a picture in an encoding or a decodingprocess excluding in-loop filtering operations.

13. The method of clause 11 or 12, wherein the syntax element issubpic_treated_as_pic_flag[i].

14. The method of clause 11 or 13, wherein the format rule specifiesthat, in case that the syntax element is not present, a value of thesyntax element is inferred to be equal to a certain value that specifiesthe i-th subpicture of each coded picture in the coded layer videosequence is treated as a picture in an encoding or a decoding processexcluding in-loop filtering operations.

15. The method of clause 14, wherein certain value is equal to 1.

16. The method of any of clause 11 to 13, wherein in case that thesyntax element is not present, the value of the syntax element isinferred to be equal to a certain value to enable a wrap-around motioncompensation.

17. The method of any of clauses 11 to 13, wherein in case that thesyntax element is not present, the value of the syntax element isinferred to be equal to a certain value to enable a horizontalwrap-around motion compensation.

18. The method of clause 11 to 13, wherein the format rule specifiesthat the value of the syntax element is inferred based on whether thepicture only consists of one subpicture and/or whether a subpicture hasa same width as the picture.

19. The method of clause 11 to 13, wherein the format rule specifiesthat the value of the syntax element is inferred based on i) a presenceof subpicture information and/or ii) a number of subpictures in thecoded layer video sequence and/or iii) another syntax element in asequence parameter set that indicates a constrain on loop filteringacross subpicture boundaries.

20. A method of video processing (e.g., method 720 as shown in FIG. 7C),comprising: performing 722 a conversion between a video comprising oneor more video regions and a bitstream of the video according to a formatrule, and wherein the format rule specifies that a sequence parameterset includes syntax elements that are related to parameters of adeblocking filter applicable to a video region.

21. The method of clause 20, wherein the syntax elements include asyntax element specifying an applicability of the deblocking_filter forthe video region.

22. The method of clause 20 or 21, wherein the format rule specifies, incase that the deblocking filter is disabled in the sequence parameterset, that a syntax element in a picture parameter set, a picture header,a slice header that relates to the deblocking_filter control has a valueequal to a certain value specifying that the deblocking filter is fullydisabled and not used for all slices.

23. The method of clause 20, wherein the syntax elements include adeblocking_filter control present flag that specifies a presence of thesyntax elements.

24. The method of clause 20, wherein the syntax elements include adeblocking mode indicator that is an N bit field where N is an integergreater than 1.

25. The method of clause 20, wherein the syntax elements include valuesof deblocking parameters t, and B.

26. The method of clause 20, wherein the format rule specifies that thesyntax elements in the sequence parameter set controls whether thedeblocking filter is enabled with 0-valued deblocking parameters.

27. The method of clause 20, wherein the format rule specifies to applythe deblocking filter at a sequence parameter set level or a pictureparameter set level or a picture header level or a slice header leveland use deblocking parameters included in the sequence parameter set.

28. The method of clause 20, wherein the format rule specifies to applythe deblocking filter at a sequence parameter set level or a pictureparameter set level or a picture header level or a slice header leveland use 0-valued deblocking parameters included in the sequenceparameter set.

29. A method of video processing (e.g., method 730 as shown in FIG. 7D),comprising: performing a conversion between a video comprising one ormore pictures comprising one or more slices and a bitstream of the videoaccording to a format rule, wherein the format rule specifies that aluma quantization parameter delta information and/or a chromaquantization parameter offset is included in both a picture header and aslice header in case that a certain condition is met.

30. The method of clause 29, wherein the format rule further specifiesthat a luma quantization parameter delta present flag indicating apresence of the luma quantization parameter delta information isincluded in at least one of the picture parameter set, the pictureheader, or the slice header.

31. The method of clause 30, wherein whether the certain condition ismet is dependent on the luma quantization parameter delta present flag.

32. The method of clause 30 or 31, wherein the format rule specifiesthat values of the luma quantization parameter delta information in thepicture header and the slice header are additive used for calculating aluma quantization parameter.

33. The method of clause 29, wherein the format rule further specifiesthat a chroma quantization parameter offsets present flag indicating apresence of the chroma quantization parameter offset is included in atleast one of the picture parameter set, the picture header, or the sliceheader.

34. The method of clause 33, wherein whether the certain condition ismet is dependent on the chroma quantization parameter offsets presentflag.

35. The method of clause 33, wherein the format rule specifies thatvalues of the chroma quantization parameter offsets in the pictureheader and the slice header are additive used for calculating a chromaquantization parameter.

36. A method of video processing, comprising: performing a conversionbetween a video comprising one or more video pictures comprising one ormore video slices and a bitstream of the video according to a formatrule, wherein the format rule specifies that a chroma quantizationparameter (QP) table applicable for conversion of a video block of thevideo is derived as an XOR operation between(delta_qp_in_val_minus1[i][j]+1) and delta_qp_ diff_val[i][j], whereindelta_qp_in_val_minus1[i][j] specifies a delta value used to derive theinput coordinate of the j-th pivot point of the i-th chroma mappingtable and delta_qp_ diff_val[i][j] specifies a delta value used toderive the output coordinate of the j-th pivot point of the i-th chromaQP mapping table, where i and j are integers.

37. A method of video processing (e.g., method 740 as shown in FIG. 7E),comprising: performing 742 a conversion between a video comprising oneor more video pictures comprising one or more video slices and abitstream of the video according to a format rule, and wherein theformat rule specifies to include a flag indicating a presence ofmultiple sets of chroma quantization parameter tables in a sequenceparameter set.

38. The method of clause 37, wherein the format rule specifies that theflag is equal to 0 in case that only one set of the chroma quantizationparameter tables is allowed to be signaled.

39. The method of clause 37, wherein the format rule specifies that theflag is equal to 1 in case that the multiple sets of the chromaquantization parameter tables are allowed to be signaled.

40. A method of video processing (e.g., method 750 as shown in FIG. 7F),comprising: performing a conversion between a video comprising one ormore video pictures comprising one or more video slices and a bitstreamof the video according to a format rule, and wherein the format rulespecifies that indication of multiple sets of chroma quantizationparameter tables is disabled for a sequence due to the sequence notincluding a slice of a particular type.

41. The method of clause 40, wherein the particular type is a B slicetype.

42. The method of clause 40, wherein the particular type is a P slicetype.

43. The method of any of clauses 1 to 42, wherein the conversionincludes encoding the video into the bitstream.

44. The method of any of clauses 1 to 42, wherein the conversionincludes decoding the video from the bitstream.

45. The method of clauses 1 to 42, wherein the conversion includesgenerating the bitstream from the video, and the method furthercomprises: storing the bitstream in a non-transitory computer-readablerecording medium.

46. A video processing apparatus comprising a processor configured toimplement a method recited in any one or more of clauses 1 to 45.

47. A method of storing a bitstream of a video, comprising, a methodrecited in any one of clauses 1 to 45, and further including storing thebitstream to a non-transitory computer-readable recording medium.

48. A computer readable medium storing program code that, when executed,causes a processor to implement a method recited in any one or more ofclauses 1 to 45.

49. A computer readable medium that stores a bitstream generatedaccording to any of the above described methods.

50. A video processing apparatus for storing a bitstream representation,wherein the video processing apparatus is configured to implement amethod recited in any one or more of clauses 1 to 45.

A third set of clauses show example embodiments of techniques discussedin the previous section (e.g., items 7-9).

1. A method of video processing (e.g., method 800 as shown in FIG. 8A),comprising: making 802 a determination, for a conversion between a videoregion of a video and a bitstream of the video, about how padding orclipping is performed for an inter-prediction process at a boundary ofthe video region according to a rule; and performing 804 the conversionbased on the determination; wherein the rule is based on at least two of(a) a type of the boundary, (b) a first parameter indicative of whethera wrap-around motion compensation is enabled, or (c) a second parameterindicating whether subpicture boundaries are treated as pictureboundaries.

2. The method of clause 1, wherein the rule specifies to apply thewraparound motion compensation during the inter-prediction processwithout considering the second parameter in case that the boundary is apicture boundary and that the first parameter is equal to a certainvalue.

3. The method of clause 1 or 2, wherein the boundary is a verticalboundary.

4. The method of clause 1 or 2, wherein the boundary type is a pictureboundary.

5. The method of clause 1 or 2, wherein the boundary type is asubpicture boundary.

6. The method of clause 1 or 2, wherein the first parameter is a syntaxflag at a picture parameter set level that specifies whether ahorizontal wrap-around motion compensation is enabled for picturesreferring to the picture parameter set.

7. The method of clause 1 or 2, wherein the second parameter is a syntaxflag at a sequence parameter set that specifies whether a subpicture ofeach coded picture in a coded layer video sequence is treated as apicture in a decoding process excluding in-loop filtering operations.

8. The method of clause 1, wherein the rule specifies to apply thewrap-around motion compensation during the inter-prediction processwithout considering the second parameter in case that both two verticalboundaries are picture boundaries and that the first parameter is equalto a certain value.

9. The method of any of clauses 1 to 8, wherein the wrap-around motioncompensation indicates horizontal wrap around padding or clipping.

10. A method of video processing (e.g., method 810 as shown in FIG. 8B),comprising: performing 812 a conversion between a video comprising oneor more pictures and a bitstream of the video according to a formatrule, wherein the format rule specifies that offsets for wrap aroundpadding or clipping for subpictures of a picture are specified at asubpicture level.

11. The method of clause 10, wherein the format rule specifies toinclude different indications for the wrap around padding or clippingfor the subpictures.

12. The method of clause 10, wherein the format rule specifies toinclude different offsets for the wrap around padding or clipping forthe subpictures.

13. The method of any of clauses 1 to 12, wherein the conversionincludes encoding the video into the bitstream.

14. The method of any of clauses 1 to 12, wherein the conversionincludes decoding the video from the bitstream.

15. The method of clauses 1 to 12, wherein the conversion includesgenerating the bitstream from the video, and the method furthercomprises: storing the bitstream in a non-transitory computer-readablerecording medium.

16. A video processing apparatus comprising a processor configured toimplement a method recited in any one or more of clauses 1 to 15.

17. A method of storing a bitstream of a video, comprising, a methodrecited in any one of clauses 1 to 15, and further including storing thebitstream to a non-transitory computer-readable recording medium.

18. A computer readable medium storing program code that, when executed,causes a processor to implement a method recited in any one or more ofclauses 1 to 15.

19. A computer readable medium that stores a bitstream generatedaccording to any of the above described methods.

20. A video processing apparatus for storing a bitstream, wherein thevideo processing apparatus is configured to implement a method recitedin any one or more of clauses 1 to 15.

A fourth set of clauses show example embodiments of techniques discussedin the previous section (e.g., item 10)

1. A method of video processing (e.g., method 900 as shown in FIG. 9 ),comprising: performing 902 a conversion between a video comprising oneor more video regions and a bitstream of the video according to a formatrule, wherein the format rule specifies that a variable X indicateswhether B slice is allowed or used in a video region, and wherein theformat rule further specifies that the variable X is based on values ofa reference picture list information present flag and/or a fieldindicating a number of entries in a reference picture list syntaxstructure.

2. The method of clause 1, wherein the video region corresponds to apicture or a slice.

3. The method of clause 1 or 2, wherein the reference picture listinformation present flag is in a picture header.

4. The method of any of clauses 1 to 3, wherein the reference picturelist information present flag is rpl_info_in_ph_flag and the fieldindicating the number of entries in the reference picture list syntaxstructure is num_ref_entries [i][RplsIdx [i]], and wherein the variableX is derived using at least one of following:

a) (rpl_info_in_ph_flag && num_ref_entries[0][RplsIdx[0]]>0 &&num_ref_entries[1][RplsIdx[1]]>0);

b) (rpl_info_in_ph_flag && num_ref_entries[1][RplsIdx[1]]>0);

c) (rpl_info_in_ph_flag && num_ref_entries[1][RplsIdx[1 ]]>1);

d) (rpl_info_in_ph_flag && num_ref_entries[1][RplsIdx[1]]>0);

e) based on a number of active reference indices to be used for a slice;or

f) based on a number of allowed reference pictures for list 1, whereby iis an integer.

5. The method of any of clauses 1 to 4, wherein the format rule furtherspecifies that signaling and/or semantics and/or inference of one ormore syntax elements included in the syntax structure corresponding to apicture header is dependent on the variable X.

6. The method of clause 5, wherein the one or more syntax elementsenable a coding tool which requires more than one prediction signal.

7. The method of clause 6, wherein the coding tool corresponds to abi-prediction, a mixed intra and inter coding, or prediction with linearor non-linear weighting from multiple prediction blocks.

8. The method of clause 6, wherein the one or more syntax elementsinclude a first syntax element indicating whether collocated picturesused for temporal motion vector prediction is derived from a referencepicture list 0 or reference picture list 1, a second syntax elementindicating whether motion vector difference coding syntax structure forlist 1 is parsed or not, a third syntax element indicating whether abi-directional optical flow coding is disabled, a fourth syntax elementindicating whether a decoder-side motion vector refinement is disabled,a fifth syntax element indicating a number of weights signalled forentries in the reference picture list 1.

9. The method of clause 8, wherein the first syntax element correspondsto ph_collocated_from_10_flag, the second syntax element corresponds toph_mvd_11_zero_flag, the third syntax element corresponds toph_disable_bdof_flag, the fourth syntax element corresponds toph_disable_dmvr_flag, and the fifth syntax element corresponds tonum_11_weights.

10. The method of clause 5, wherein the format rule further specifiesthat, only in case that the variable X indicates that the picturecontains one or more B slices, the one or more syntax elements areincluded.

11. The method of clause 5, wherein the format rule further specifiesthat in case that the variable X indicates that the picture contains noB slices, the one or more syntax elements are skipped.

12. The method of clause 5, wherein the format rule further specifieswhether to signal the one or more syntax elements are based on thevariable X.

13. The method of clause 5, wherein the format rule further specifiesthat when the variable X is equal to 0 and a syntax element indicatingwhether motion vector difference coding syntax structure is parsed ornot is not signaled, a value of the syntax element is inferred to beequal to a certain value.

14. The method of clause 13, wherein the format rule further specifiesthat when the variable X being set to “rpl_info_in_ph_flag” is equal to0, the value of the syntax element is inferred to be equal to 1.

15. The method of clause 13, wherein the format rule further specifiesthat when the variable X being set to“num_ref_entries[1][RplsIdx[1]] >0” is equal to 0, the value of thesyntax element is inferred to be equal to 1.

16. The method of clause 5, wherein the format rule further specifiesthat the inference of the one or more syntax elements is dependent on avalue of the variable X.

17. The method of clause 16, wherein the one or more syntax elementsinclude a PH (picture header) syntax element indicating whether abi-directional optical flow coding is disabled and wherein the formatrule specifies that a value of the PH syntax element is inferred basedon the value of the variable X.

18. The method of clause 16, wherein the one or more syntax elementsinclude a PH (picture header) syntax element indicating whether adecoder-side motion vector refinement is disabled and wherein the formatrule specifies that a value of the PH syntax element is inferred basedon the value of the variable X.

19. The method of clause 16, wherein the one or more syntax elementsinclude a PH (picture header) syntax element indicating whethercollocated pictures used for temporal motion vector prediction isderived from a reference picture list 1 or a reference picture list 0and wherein the format rule specifies that a value of the PH syntaxelement is inferred to be equal to a certain value in case of satisfying(1) a value of another PH syntax element indicating an applicability oftemporal motion vector predictor to a picture is equal to 1, (2) a valueof the reference picture list information present flag in a pictureheader is equal to 1, and (3) the value of the variable X is equal to 0.

20. The method of clause 19, wherein the value of the PH (pictureheader) syntax element is inferred to be equal to 0 in case ofsatisfying (1) the value of another PH syntax element indicating theapplicability of temporal motion vector predictor to the picture isequal to 1, (2) the value of the reference picture list informationpresent flag in a picture header is equal to 1, and (3) the variable Xbeing set to “num_ref_entries[1][RplsIdx[1]]>0” is equal to 0.

21. The method of clause 16, wherein the one or more syntax elementsinclude a PH (picture header) syntax element indicating a number ofweights signalled for entries in the reference picture list land whereinthe format rule specifies that a value of the PH syntax element isinferred to be equal to a certain value in case that the variable X isequal to a certain value.

22. The method of clause 21, wherein the value of the PH syntax elementis inferred to be equal to 0 in case that the variable X being set to“num_ref_entries[1][RplsIdx[1]] >0” is equal to 0.

23. The method of clause 22, wherein when the value of the PH syntaxelement is inferred to be equal to 0, weighted prediction parameters forthe reference picture list 1 are not signalled in a picture header orslice headers of a picture.

24. The method of any of clauses 1 to 23, wherein the conversionincludes encoding the video into the bitstream.

25. The method of any of clauses 1 to 23, wherein the conversionincludes decoding the video from the bitstream.

26. The method of clauses 1 to 23, wherein the conversion includesgenerating the bitstream from the video, and the method furthercomprises: storing the bitstream in a non-transitory computer-readablerecording medium.

27. A video processing apparatus comprising a processor configured toimplement a method recited in any one or more of clauses 1 to 26.

28. A method of storing a bitstream of a video, comprising, a methodrecited in any one of clauses 1 to 26, and further including storing thebitstream to a non-transitory computer-readable recording medium.

29. A computer readable medium storing program code that, when executed,causes a processor to implement a method recited in any one or more ofclauses 1 to 26.

30. A computer readable medium that stores a bitstream generatedaccording to any of the above described methods.

31. A video processing apparatus for storing a bitstream representation,wherein the video processing apparatus is configured to implement amethod recited in any one or more of clauses 1 to 26.

In the present document, the term “video processing” may refer to videoencoding, video decoding, video compression or video decompression. Forexample, video compression algorithms may be applied during conversionfrom pixel representation of a video to a corresponding bitstreamrepresentation or vice versa. The bitstream representation of a currentvideo block may, for example, correspond to bits that are eitherco-located or spread in different places within the bitstream, as isdefined by the syntax. For example, a macroblock may be encoded in termsof transformed and coded error residual values and also using bits inheaders and other fields in the bitstream. Furthermore, duringconversion, a decoder may parse a bitstream with the knowledge that somefields may be present, or absent, based on the determination, as isdescribed in the above solutions. Similarly, an encoder may determinethat certain syntax fields are or are not to be included and generatethe coded representation accordingly by including or excluding thesyntax fields from the coded representation.

The disclosed and other solutions, examples, embodiments, modules andthe functional operations described in this document can be implementedin digital electronic circuitry, or in computer software, firmware, orhardware, including the structures disclosed in this document and theirstructural equivalents, or in combinations of one or more of them. Thedisclosed and other embodiments can be implemented as one or morecomputer program products, i.e., one or more modules of computer programinstructions encoded on a computer readable medium for execution by, orto control the operation of, data processing apparatus. The computerreadable medium can be a machine-readable storage device, amachine-readable storage substrate, a memory device, a composition ofmatter effecting a machine-readable propagated signal, or a combinationof one or more them. The term “data processing apparatus” encompassesall apparatus, devices, and machines for processing data, including byway of example a programmable processor, a computer, or multipleprocessors or computers. The apparatus can include, in addition tohardware, code that creates an execution environment for the computerprogram in question, e.g., code that constitutes processor firmware, aprotocol stack, a database management system, an operating system, or acombination of one or more of them. A propagated signal is anartificially generated signal, e.g., a machine-generated electrical,optical, or electromagnetic signal, that is generated to encodeinformation for transmission to suitable receiver apparatus.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a stand-alone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

The processes and logic flows described in this document can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., a field programmable gate array (FPGA) or anapplication specific integrated circuit (ASIC).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random-access memory or both. The essential elements of a computer area processor for performing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto optical disks, or optical disks. However, a computerneed not have such devices. Computer readable media suitable for storingcomputer program instructions and data include all forms of non-volatilememory, media and memory devices, including by way of examplesemiconductor memory devices, e.g., erasable programmable read-onlymemory (EPROM), electrically erasable programmable read-only memory(EEPROM), and flash memory devices; magnetic disks, e.g., internal harddisks or removable disks; magneto optical disks; and compact disc,read-only memory (CD ROM) and digital versatile disc read-only memory(DVD-ROM) disks. The processor and the memory can be supplemented by, orincorporated in, special purpose logic circuitry.

While the present disclosure contains many specifics, these should notbe construed as limitations on the scope of any subject matter or ofwhat may be claimed, but rather as descriptions of features that may bespecific to particular embodiments of particular techniques. Certainfeatures that are described in the present disclosure in the context ofseparate embodiments can also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment can also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Moreover, the separation of various system components in theembodiments described in the present disclosure should not be understoodas requiring such separation in all embodiments.

Only a few implementations and examples are described and otherimplementations, enhancements and variations can be made based on whatis described and illustrated in the present disclosure.

What is claimed is:
 1. A method of video processing, comprising:performing a conversion between a video comprising one or more videoregions and a bitstream of the video according to a format rule, whereinthe format rule specifies that a first syntax element indicates whethera bi-directional optical flow inter prediction based inter bi-predictionis disabled for a video region of the one or more video regions, andwherein the format rule further specifies that a presence in a pictureheader of the first syntax element is based on values of a second syntaxelement which is a reference picture list information present flag thatindicates whether the reference picture list information is present inthe picture header and a third syntax element indicating a number ofentries in a reference picture list syntax structure.
 2. The method ofclaim 1, wherein a video region of the one or more video regionscorresponds to a picture or a slice.
 3. The method of claim 1, whereinthe second syntax element is rpl_info_in_ph_flag and the third syntaxelement is num_ref_entries [i][RplsIdx[i]], wherein i is an integer, andwherein the first syntax element is present in the picture header atleast based on (rpl_info_in_ph_flag &&num_ref_entries[1][RplsIdx[1]]>0), whereinnum_ref_entries[1][RplsIdx[1]] indicates that the number of entries inthe RplsIdx[1]-th reference picture list syntax structure for areference picture list
 1. 4. The method of claim 3, wherein the firstsyntax element being present in the picture header is further based on avalue of a fourth syntax element indicating that the first syntaxelement is allowed to be present.
 5. The method of claim 1, wherein theformat rule further specifies that a presence in the picture header of afifth syntax element indicating whether a decoder-side motion vectorrefinement is disabled is based on the values of the second syntaxelement and the third syntax element.
 6. The method of claim 5, whereinthe fifth syntax element is present in the picture header, when a valueof a sixth syntax element indicates that the fifth syntax element isallowed to be present, a value of the second syntax elementrpl_info_in_ph_flag is equal to 1 and a value of the third syntaxelement num_ref_entries[1][RplsIdx[1]] is greater than
 1. 7. The methodof claim 1, wherein the format rule further specifies that a presence inthe picture header of a seventh syntax element indicating whether motionvector difference coding syntax structure for list 1 is parsed or not isat least based on that a value of the second syntax elementrpl_info_in_ph_flag is equal to 1 and a value of the third syntaxelement num_ref_entries[1][RplsIdx[1]] is greater than
 1. 8. The methodof claim 1, wherein the format rule further specifies that a presence inthe picture header of an eighth syntax element indicating whethercollocated pictures used for temporal motion vector prediction isderived from a reference picture list 0 or reference picture list 1 isat least based on that a value of the second syntax elementrpl_info_in_ph_flag is equal to 1 and a value of the third syntaxelement num_ref_entries[1][RplsIdx[1]] is greater than
 1. 9. The methodof claim 8, wherein the format rule further specifies that when a valueof a ninth syntax element indicates that a temporal motion vectorpredictor is enabled, the value of the second syntax elementrpl_info_in_ph_flag is equal to 1 and the value of the third syntaxelement num_ref_entries[1][RplsIdx[1]] is equal to 0, the value of theeighth syntax element is inferred to be equal to 1 which indicates thatthe collocated pictures used for temporal motion vector prediction isderived from the reference picture list
 0. 10. The method of claim 1,wherein the format rule further specifies that a presence in the pictureheader of a tenth syntax element indicating a number of weightssignalled for entries in a reference picture list 1 is at least based onthat a value of the second syntax element rpl_info_in_ph_flag is equalto 1 and a value of the third syntax elementnum_ref_entries[1][RplsIdx[1]] is greater than
 1. 11. The method ofclaim 1, wherein the format rule further specifies that a presence of aneleventh syntax element in a sequence parameter set that indicates aconstraint on loop filtering across subpicture boundaries is based onwhether a number of subpictures in a picture is greater than 1, whereinthe eleventh syntax element equal to 1 specifies that all subpictureboundaries in a coded layer video sequence are treated as pictureboundaries and there is no loop filtering across the subpictureboundaries, wherein the eleventh syntax element is not present in casethat the number of subpictures in the picture is equal to 1, and whereinin case that the eleventh syntax element is not present, a value of theeleventh syntax element is inferred to be equal to
 1. 12. The method ofclaim 1, wherein the format rule further specifies that in case that atwelfth syntax element is not present, a value of the twelfth syntaxelement is inferred to be equal to 1 that specifies an i-th subpictureof each coded picture in a coded layer video sequence is treated as apicture in an encoding or a decoding process excluding in-loop filteringoperations, wherein i is an integer.
 13. The method of claim 12, whereinthe format rule further specifies that during an inter-predictionprocess, how clipping is performed at a boundary of a video region ofthe one or more video regions is based on a thirteenth syntax element ata picture parameter set level, specifying whether a horizontalwrap-around motion compensation is enabled for pictures referring to apicture parameter set and the twelfth syntax element at a sequenceparameter set level.
 14. The method of claim 1, wherein the conversionincludes encoding the video into the bitstream.
 15. The method of claim1, wherein the conversion includes decoding the video from thebitstream.
 16. An apparatus for processing video data comprising aprocessor and a non-transitory memory with instructions thereon, whereinthe instructions upon execution by the processor, cause the processorto: perform a conversion between a video comprising one or more videoregions and a bitstream of the video according to a format rule, whereinthe format rule specifies that a first syntax element indicates whethera bi-directional optical flow inter prediction based inter bi-predictionis disabled for a video region of the one or more video regions, andwherein the format rule further specifies that a presence in a pictureheader of the first syntax element is based on values of a second syntaxelement which is a reference picture list information present flag thatindicates whether the reference picture list information is present inthe picture header and a third syntax element indicating a number ofentries in a reference picture list syntax structure.
 17. The apparatusof claim 16, wherein a video region of the one or more video regionscorresponds to a picture or a slice, wherein the second syntax elementis rpl_info_in ph_flag and the third syntax element is num_ref_entries[i][RplsIdx [i]], wherein i is an integer, wherein the first syntaxelement is present in the picture header at least based on(rpl_info_in_ph_flag && num_ref_entries[1][RplsIdx[1]] >0), whereinnum_ref_entries[1][RplsIdx[1]] indicates that the number of entries inthe RplsIdx[1]-th reference picture list syntax structure for areference picture list 1, and wherein the first syntax element beingpresent in the picture header is further based on a value of a fourthsyntax element indicating that the first syntax element is allowed to bepresent.
 18. The apparatus of claim 16, wherein the format rule furtherspecifies that a presence in the picture header of a fifth syntaxelement indicating whether a decoder-side motion vector refinement isdisabled is based on the values of the second syntax element and thethird syntax element, and wherein the fifth syntax element is present inthe picture header, when a value of a sixth syntax element indicatesthat the fifth syntax element is allowed to be present, a value of thesecond syntax element rpl_info_in_ph_flag is equal to 1 and a value ofthe third syntax element num_ref_entries[1][RplsIdx[1]] is greaterthan
 1. 19. A non-transitory computer-readable storage medium storinginstructions that cause a processor to: perform a conversion between avideo comprising one or more video regions and a bitstream of the videoaccording to a format rule, wherein the format rule specifies that afirst syntax element indicates whether a bi-directional optical flowinter prediction based inter bi-prediction is disabled for a videoregion of the one or more video regions, and wherein the format rulefurther specifies that a presence in a picture header of the firstsyntax element is based on values of a second syntax element which is areference picture list information present flag that indicates whetherthe reference picture list information is present in the picture headerand a third syntax element indicating a number of entries in a referencepicture list syntax structure.
 20. A non-transitory computer-readablerecording medium storing a bitstream of a video which is generated by amethod performed by a video processing apparatus, wherein the methodcomprises: generating the bitstream of the video comprising one or morevideo regions according to a format rule, wherein the format rulespecifies that a first syntax element indicates whether a bi-directionaloptical flow inter prediction based inter bi-prediction is disabled fora video region of the one or more video regions, and wherein the formatrule further specifies that a presence in a picture header of the firstsyntax element is based on values of a second syntax element which is areference picture list information present flag that indicates whetherthe reference picture list information is present in the picture headerand a third syntax element indicating a number of entries in a referencepicture list syntax structure.